An environmental study of a hygiene substance used in animal buildings

 
Finn Eiland (D.Sc., Head of department)
Danish Institute of Agricultural Sciences
Department of Crop Physiology and Soil Science
Research Centre Foulum
P.O. Box 50
DK-8830 Tjele
Dir tel: +45 8999 1862
Fax +45 8999 1619
E-mail: finn.eiland@agrsci.dk

Contents

• Introduction

• Materials and methods

  • Slurry types and addition of Stalosan^® F

  • Field experiments

  • Samplings of slurry, soil and crops

  • Slurry

  • Soil

  • Crops

  • Chemical methods

  • Soil and slurry analyses

  • Microbiological methods

• Results and discussions

  • Chemical parameters in soil

  • Copper in the environment

  • The soil microorganisms and their activity in soil

  • Microbiological parameters in soil

  • Chemical parameters measured in slurry

  • Microbiological parameters measured in slurry

  • Yields of ryegrass

  • Copper content in ryegrass

• Conclusions (in English)

• Konklusioner (in Danish)

• Conclusions (in German)

• Conclusions (in Spanish)

• Conclusions (in French)

• Acknowledgements

• References

Introduction

The microorganisms in agricultural soils are affected by several factors, such as manuring, cultivation, croprotation and weather conditions. The factors all affect soil fertility and productivity (Alexander, 1977). Soil microorganisms play an important role in the growth of plants and they are responsible for e.g. the decomposition of dead material and for nutrient transformation. The understanding of nutrient transformations (e.g. carbon and nitrogen turnover) in complex systems such as a soil requires information about microbial biomass, microbial activity and enzymatic activity as well as nitrogen processes.
In most soils the microbial biomass comprises about 1-3% of the total soil organic matter and there is a reasonably close linear relationship between amounts of biomass and amounts of soil organic matter (Jenkinson & Ladd, 1981). The microbial biomass responds much more quickly than does soil organic matter as a whole to changes in soil management. The long-term effects of organic manure and NPK fertilizers on soil microorganisms have been examined to some extent in long-term fertilization experiments at Askov Experimental Station (e.g. Eiland 1980, 1981). Furthermore, the effects on soil microorganisms of the addition of various compounds (e.g. sewage sludge, heavy metals, pesticides and oil) to the fields can be evaluated by microbiological methods.
In pig- and cattle buildings, the dry powder Stalosan^® F (Sta.-F) is used as a hygiene agent. The residues from the product remaining in the slurry will be transported from the animal house to the slurry tank and finally to the field. The positive effect of Sta.-F as a hygiene agent in reducing the number of bacteria, fungi, virus and sporulation rates of unsporulated coccidians oocysts from infected chickens (the coccidians infect the intestinal or blood cells and causing coccidioses) has been documented in several studies performed at different international and national laboratories for the company Stormøllen A/S. The effect of Sta.-F is obtained by an adsorptive bond of the pathogens to the minerals in the product, which is suppose to cause a strong reduction of the these organisms on surfaces of animal houses (Methling et al., 1997). Furthermore, the disinfectant has proved useful in reducing moisture, ammonia emission and H2S in animal buildings. It has also been shown that adding Sta.-F to cattle slurry can reduce ammonia emission by up to 60% (Anderson, 1994). The product both absorbs ammonia and reduces the conversion of urea to ammonia. However, very little has been known about the long-term effect of Sta.-F on the soil environments, when the residues of the product will be applied to the field through the slurry for many years.
The main purpose of this study was to examine the microbiological and chemical conditions in the soil after using St.-F in animal houses with pigs (sows and piglets) and after adding Sta.-F directly to the slurry immediately before the slurry was transferred to field plots. The experiment also included plots receiving only inorganic fertilizer and a combination of inorganic fertilizer and Sta.-F. In addition, chemical and microbiological tests were performed on the different slurry types, and crop yields and Cu content in the crop were also measured.

Material and methods

Slurry types and addition of Stalosan^® F

Slurry 1 (Foulum slurry) Different amounts of Sta.-F. were added to the slurry from a pigfarm: 1) without addition of Sta.-F, 2) addition of 0.5 kg Sta.-F T^-1 slurry (normal amount) and 3) addition of 5 kg Sta.-F T^-1 slurry (10 times normal amount). This farm does not use Sta.-F in the animal building.
The amount of Sta.-F added to the slurry to reflect the real situation in agriculture, was calculated from the amount of Sta.-F given as 50 g per m² and number of times per week in the animal building.
Slurry 2. From a pigfarm (sows with piglets), where the farmer frequently used Sta.-F in the animal building.

Field experiments

At Research Centre Foulum (sandy loam soil), slurry without and with Sta.-F was applied to a crop of ryegrass in spring 1997 and 1998. The size of the plots was 6 x 10 m and two replicate plots were randomly chosen by using a statistical program.

The different treatments were :

1. 30 T slurry - 0 kg Stalosan^® F

2. 30 T slurry containing 15 kg Stalosan^® F ha^-1 (normal amount)

3. 30 T slurry containing 150 kg Stalosan^® F ha^-1 (10 x normal amount)
    

4. 90 T slurry - 0 kg Stalosan^® F

5. 90 T slurry containing 45 kg Stalosan^® F ha^-1 (normal amount)

6. 90 T slurry containing 450 kg Stalosan^® F ha^-1 (30 x normal amount)
    

7. 30 T slurry ha^-1 - Stalosan^® F used in animal building (slurry 2)

8. 90 T slurry ha^-1 - Stalosan^® F used in animal building (slurry 2)
    

9. Inorganic fertilizer - 50 kg N ha^-1 cut^-1 (3 cuts) - 0 kg Stalosan^® F

10. Inorganic fertilizer - 50 kg N ha^-1 cut^-1 (3 cuts) + 150 kg Stalosan^® F ha^-1 (plots established 1998)

11. Inorganic fertilizer - 50 kg N ha^-1 cut^-1 (3 cuts) + 450 kg Stalosan^® F ha^-1 (plots established 1998)

In 1998, inorganic fertilizer (50 kg N ha^-1 of calcium ammonium nitrate, CAN) was applied to the plots no. 9,10 and 11 on 5 May 5. To obtain reliable crop yields in second and third cuts of ryegrass, 50 kg N ha^-1 of CAN was applied to all plots on 9 June and 25 August, respectively.
Addition of slurry: 29 April 1997 and 29 April 1998;
Crops: Ryegrass in 1997 and 1998. Winterwheat was sown in October 1998 after rotavation (23 September), ploughing and harrowing (24 September). Winterwheat will be the crop in an extended experiment for 1999 and year 2000.

Samplings of slurry, soil and crops

Slurry
To obtain representative subsamples of the slurry, 50 L was taken from a slurry-spreader with a stirrer. The slurry was then stirred with a motorised hand stirrer and 10 subsamples were transferred to an 1 L bottle. Chemical and microbiological studies of the four different slurry types were initiated at the time when slurry was added to the field plots.

Soil

Soil samples were taken at the 0-5 cm depth, 7 July 1997, and at 0-5 cm and 5-20 cm depth, 12 February 1998 and 24 August 1998, respectively. Measurements for chemical and microbiological analyses were performed on profile samples taken on 24 August1998 at 25-50 cm, 50-75 cm and 75-100 cm depths, respectively. In the two upper profiles, twelve samples were taken from each plot and mixed into one sample. In the deeper soil layers, four samples were drawn from each plot and mixed into one sample.
All soil samples used for chemical and microbiological analyses were sieved through a 4 mm sieve before the analyses took place. The soil samples taken in July 1997 were very dry. Therefore, water was adjusted to 60% of the water holding capacity and incubated for 3 days at 20^oC before these samples were analysed for microbiological parameters.

Crops

Ryegrass was harvested on the following dates: (10 June, 24 July and 27 October 27 1997) and (3 June, 13 July and 24 August 1998).
Fresh and dry weight of ryegrass were measured from each treatment. Furthermore, the content of crop uptake of Cu with each treatment was analysed.

Chemical methods

Soil and slurry analyses
An alkaline persulphate oxidation method with flow injection analysis was used for determination of total N in soil samples (Eiland & Nielsen, 1996). In slurry total nitrogen was determined by Kjeldahl digestion and destillation of ammonium (Bremner & Mulvany, 1982). Ammonium N was determined spectrophotometrically (660 nm) on an autoanalyser after a complex formation with salicylate and dichlorisocyanorate (Crooke & Simpson, 1971). Nitrate N was measured spectrophotometrically (520 nm) in an autoanalyzer (Tecator) after a reduction to nitrite with hydrazine and an azo colourization (Best, 1976). Total carbon was determined by dry combustion (1200^oC) according to Ter Meulen (Tabatabai & Bremner, 1970). pH (CaCl₂) was measured in a solution of 10 g soil and 25 ml of a 0.01 M CaCl₂-solution. In slurry pH was measured directly in the solution. Electrical conductivity (EC) was measured in ohm. P (Ft) was extracted with 0.2 N sulphuric acid and P content measured spectrophotometrically. In slurry, P was determined colometrically after formation of a coloured complex. K (Kt) was extracted with ammonium-acetate solution and measured with flame-photometry. K in slurry was analysed by destruction and measurement on a flame-photometer. Total SO₄-S in slurry was analysed according to Nes (1979). Cl in slurry was determined as described by LaCroix et al. (1970). Zn (Znt) and Cu (Cut) in the soil were extracted with an EDTA-solution and measured with atomic absorption spectrophotometry. In slurry, total Zn and total Cu were determined as described by Milner and Whiteside (1988). The main part of the chemical analyses was carried out according to Danish standard procedures (Anonymous, 1994).

Microbiological methods

The microbial biomass was measured by the ATP method. ATP content in soil was extracted with sulphuric acid-phosphate and NRB^® and measured in a Lumacounter 2080^® by the luciferin-luciferase method as described by Eiland (1983, 1985). The method was also used for the slurry samples with the following modifications: samples of slurry weighing 1 g were stored at 200C for 2 hours before measurement. The extraction was performed with 15 ml sulphuric acid-phosphate and NRB^® for the samples, and for the standards 14 ml of the extractant plus 1 ml ATP-standard solution (2 to 6 μg ml^-1) was used. After shaking for 15 min., 0.2 ml of each suspension was transferred to 9.8 ml Tris-buffer (on ice). Then 50 μl of the latter solution was transferred to 50 μl of NRB^® for measurement.
The number of acridine orange stained bacteria was measured using orange staining as described by Eiland (1985) with an epifluorescent microscope (magnification 788x, oil immersion objective, 100x, NA 1.25). Two slides were prepared from each replicate sample and 20 microscope fields were counted on each slide.
The CO₂-evolution rate was determined by placing 15 g soil portions in 300 ml bottles sealed with a septum and measuring the increase in CO₂ concentration after a fixed time (1 day of incubation at 20^oC) by gas chromatography using a thermal conductivity detector. The column was a Porapak N (6.0 mm x 1.0 m), used at an oven temperature of 60^oC; the detector temperature was 50^oC, and the carrier gas was He with a flow of 64 ml min^-1. The calibration was performed by atmospheric CO₂ content (0.036%). Samples of slurry weighing 10 g were added to 100 ml glass bottles and there were placed in 2 L glass bottles. The air was replaced with N₂ and the cap, sealed with a septum, was closed and incubated for 1, 3, 24 and 72 h, respectively, before the CO₂ content was measured. At certain intervals the N₂-air was replaced.
Dehydrogenase activity in soil was determined by a modified method of Curl & Sandberg (1961) as described by Eiland et al. (1979). INT (2-p-iodophenyl-3-p-nitrophenyl-5-phenyl-tetrazolium chloride) was used as an H acceptor for estimating respiratory potential. Slurry samples were measured by use of 5 g slurry filled up to 100 g with buffer solution in a polyethylen bag and shaken for 30 s in a Stohmacher^®. Then 1 g of the suspension was transferred to centrifuge tubes and the reaction mixtures were added (2 ml phosphate-buffer, 1 ml Na-succinate and 1 ml INT). The further procedure was similar to the method for the soil samples. The samples were measured at a spectrophotometer at 490 nm. The reaction is fast and sensitive and independent of oxygen status.
Potentiel nitrification activity was determined by a modified procedure of the slurry/ClO₃ block assay (Staley et al., 1990) as follows: 15 g wet soil portions (3 replicates) were weight out into 330 ml infusion flasks. Fifty ml of NH₄ buffer solution plus 1 ml of 1.0 M NaClO₃ was added to the samples and incubated for 24 h at 20^oC on a shaker. Then the samples were hand-shaken, transferred to filters (Whatmann no. 1) and filtrated into flasks (7.5 x 4.5 cm diam.). The filtration was performed at 2^oC in flamingo-boxes containing ice and water. NO₂ in the sample extracts was measured on a flow injection equipment (FIA) at 540 nm.

Results and discussions

Chemical parameters in soil

Chemical characteristics of the soil are shown in Tables 1, 2 and 3a,b. The first samples were taken 2½ month after the field plots received slurry in year one (17 July 1997). To evaluate possible long-term effects, a second set of soil samples was taken 9½ month after addition of slurry (12 February 1998). The third set of soil samples was taken 4 months after addition of slurry in the second year.
Soil pH increased slightly after addition of 90 T slurry ha^-1 compared to the corresponding treatment with addition of 30 T slurry ha^-1 (sampling event 1 and 2). In the third sampling very similar pH-values were found for the different treatment loaded with slurry at the same soil depth. pH decreased at the 50-100 cm depth compared to the surface layers. The content of Sta.-F did not influence the measurements at any sampling time.
The content of total C was higher in treatments added 90 T slurry ha^-1 than in treatment added 30 T slurry ha^-1 (sampling event 3). There was a tendency for an increased C content in treatments added slurry with Sta.-F in 30 T slurry but only minor differences in total C were observed in the corresponding treatments with 90 T slurry. The content of total N in the different treatments was at the same level in the plough layer for all treatments.
The contents of plant available P (Ft) were also influenced by the amount of slurry added to the land and Sta.-F only influenced the available P content by loading of 90 T slurry. SO₄-S increased significantly in the slurry as a result of adding Sta.-F. This could be the reason for the improved crop yields found in field treatments added Sta.- F (see Fig. 7a,b,c). Cases of sulphur deficiency have in the last decade been observed in Danish agriculture. Zn and Cu (EDTA - extractable) increased by addition of 90 T slurry compared to 30 T added. These plant micro-nutrients were not influenced By Sta.-F, when 30 T slurry was added. Adding 90 T slurry with Sta.-F resulted in an increased concentration.

Table 1. Soil chemical parameters (sampling date 17-7-1997)
Table 2. Soil chemical parameters (sampling date 12-2-1998)
Table 3a. Soil chemical parameters (sampling date 24-8-1998)
Table 3b. Soil chemical parameters (sampling date 24-8-1998)

Copper in the environment

In the Foulum field experiment (sampling August 1998), available Cu as an average of results from 0-5 cm the 5-20 cm depth varied between 3.9 and 4.9 mg kg^-1 d.w. soil in the reference soils (Table 3a,b). The highest Cu contents for all treatments were found in the surface layer and were slightly lower in the 5-20 cm layer. Below the plough layer (25-50 cm) fairly high Cu contents were still measured. In the 50-75 cm layer (30 T slurry without and with Sta.-F), Cu content was below 0.8 mg kg^-1. When 90 T slurry was applied (50-75 cm) somewhat higher values of 2.5 to 2.7 mg kg^-1 were measured in two of the treatments (slurry inc. 45 kg Sta.-F ha^-1 and slurry from animal house). In the field plot receiving only inorganic fertilizer, the Cu content was 1.1 mg kg^-1. It is likely that the variations in the Cu contents are due to differences in the soil matrix in this layer and the occasionally high values are probably not related to the use of Sta.-F. In the 75-100 cm layer only 0-0.3 mg Cu kg^-1 soil was found in all treatments.
Adding 30 T slurry ha^-1 with Sta.-F in normal and 10 x normal amounts, no measurable differences of the available Cu content were found, compared with the manured reference soil at the different depths. Adding 90 T, Sta.-F (45 and 450 kg ha^-1) increased the Cu content compared with the manured reference soil in the plough layer and in some cases in the 25-50 cm layer. It should be emphasised that such high concentrations of both slurry and Sta.-F are not related to practical farming. Normally, slurry is added in amounts not exceeding 30 T ha^-1.
The slurry without Sta.-F (30 T) contained 620 g Cu, which originates from pigfeed (Table 4). When adding 90 T slurry to the field plots, 1860 g Cu ha^-1 was added to the soil. Sta.-F in normal amounts (15 kg Sta.-F in 30 T slurry) contributed 55- 65 g Cu ha^-1 (calculated from slurry with 5 and 0.5 kg Sta.-F T^-1 in 1998; Table 4). These small amounts cannot be measured in the fraction of plant available Cu in the soil (55 g Cu ha^-1 is equivalent to 0.02 mg Cu kg^-1 soil). Thus Sta.-F can contribute 9-10% of the total Cu in slurry. It is assumed that pigfarms (sows and piglets) use higher amounts of Sta.-F than other animal productions.
In Fig. 5 is shown the total Cu content in the slurries without and with different concentrations of Sta.-F (1998 slurry). When 30 T slurry contained 150 kg Sta.-F (10 x normal amount) and 90 T contained 450 kg Sta.-F, the Cu contents increased by 552 and 1656 g Cu ha^-1, respectively. Most crops remove 20-50 g Cu ha^-1 yr^-1 (e.g. Kofoed, 1980), which is in the order of magnitude of the Cu added by Sta.-F. In the Foulum experiment with ryegrass and three cuts, 53-57 g Cu ha^-1 was removed from treatments adding 30 T slurry in 1998 (Table 5). The amount is dependent on the Cu content in the soil and crop yields (7a,b,c). When the Cu content reaches a high level in the soil, there is a risk that Cu will affect the soil microorganisms in relation to funtional diversity and this can result in a reduced ability of the microorganisms to decompose organic matter in the soil.
The total Cu content in soil consists of fixed Cu (in soil minerals and adsorbed to clay and humus), and a plant-available fraction (EDTA-extractable Cu). In Denmark the current limits for addition of Cu to the soil is 40 mg total Cu kg^-1 d.w. soil (EU limit is 140 mg total Cu kg^-1 d.w. soil). Assuming an average total Cu content of 10 mg Cu kg^-1 soil, there is space for further 30 mg kg^-1 soil, which is equivalent to 84 kg Cu ha^-1, before the Danish limitation is reached. Available Cu contents in Danish soils range from 1 to 10 mg Cu kg-1 d.w. soil. Crop yield response to applied Cu has not been observed when available Cu exceeded 3 mg Cu kg^-1 d.w. soil (Kofoed, 1980). This amount is equivalent to 8.4 kg Cu ha-1 in the 0-20 cm soil layer, assuming that one ha contains 2800 T d.w. soil.
It can be concluded that by application of Sta.-F in the amounts suggested by the company, there is only a moderate increase of Cu content in the slurry, which results in Cu loading to the land of about 60 g Cu ha^-1 yr^-1. High loading of Sta.-F in slurry (e.g. 10 times the normal amount of Sta.-F directly in the slurry tank) and addition of e.g. 30 T slurry ha^-1 (150 kg Sta.-F ha^-1) resulted in an accumulation of 1.2 kg Cu ha^-1 in the soil. Cu originated from Sta.-F was 550 g.

The soil microorganisms and their activity in soil.

The microbial biomass (ATP content) in soil includes bacteria, fungi, algae and protozoa. Bacteria and fungi predominate in numbers and in the variety of activities over the other groups of microorganisms. The activity of the soil biomass seems to be limited by the amounts of easily available carbon compounds in soil. Therefore the size of the microbial biomass does not necessarily give a measure of the microbial activity. It is necessary to measure the overall microbial activity e.g. by CO₂ evolution. The enzyme dehydrogenase activity is also a measure of microbial activity, which has proved useful in soil studies.
The microbial biomass and the microbial activity can be combined as a measure of the activity-level of the microorganisms (specific activity). The nitrification activity in a soil is performed by only a few bacteria-species acting in the nitrogen cycling. Some recent studies in our laboratory suggest that measuring potential nitrification activity can be a more sensitive method than microbial biomass and activity to detect negative effects of compounds added to soil. Therefore this method has been included in the sampling event in August 1998.

Microbiological parameters in the soil

Soil samples were taken (0-5 cm depth; sampling time 17 July 1997) in the field plots about 10 weeks after slurry was added to the plots. The microbial biomass (ATP-content) and the microbial activity (CO₂-production) were higher in field plots receiving 90 T slurry than after addition of 30 T slurry ha^-1 (Fig. 1a). It was found both with the slurry containing Sta.-F and with the slurry, where Sta.-F has been used in the animal building. The field treatment added only inorganic fertilizer contained the lowest biomass, and the microbial activity was at the same level as in soil added 30 T slurry ha^-1 without Sta.-F.
The normal amount of Sta.-F in slurry (30 T slurry ha^-1) increased slightly both the microbial biomass and microbial activity compared to the treatment receiving slurry without Sta.-F. Adding 90 T slurry ha^-1, the microbial biomass was at the same level without and with Sta.-F in a normal amount. An addition of 90 T slurry ha^-1 with the highest amount of Sta.-F, slightly reduced the biomass compared to the reference treatments without Sta.-F. The microbial activity in treatments with 90 T slurry ha^-1 was reduced by the presence of Sta.-F in the slurry.
 

Dehydrogenase-activity was reduced in treatment with 10 x normal amount of Sta.-F. (Fig. 1b). The specific activity showed that the activity level of the microbial biomass was reduced in treatments added 90 T with Sta.-F, as compared to the manured reference treatments (Fig. 1b).
The long-term effect on microbial biomass of addition of different concentrations of slurry and Sta.-F to the field plots (Spring 1997) was examined by a sampling event in February 1998. The microbial biomass (ATP-content) was very similar in all field plots (Fig. 2a). Only a slightly higher biomass was found in the 0-5 cm layer than at the 5-20 cm depth.
CO₂ evolution was higher at the 0-5 cm depth than at the 5-20 cm depth in the treatments added Sta.-F (Fig. 2a). Slurry (30 T slurry) with Sta.-F resulted in a slightly higher microbial activity than the reference soil. The addition of 90 T slurry with the highest Sta.-F addition reduced the activity in the surface layer. On the other hand, Sta.-F increased the CO₂ evolution in the 5-20 cm layer.
Dehydrogenase activity (Fig. 2b) increased in treatments added Sta.-F compared to the reference soil. There were only minor differences between the two depths.
The specific activity (Fig. 2b) showed patterns similar to those found in the dehydrogenase activity measurements.
The main sampling event was performed August 24-1998. At that time slurries without and with Sta.-F had been added to the same field plots for a two-year period. It is necessary to examine the microbial parameters for several years to obtain results which reflect the real situation in agriculture. Furthermore, the climatic conditions influence the measured parameters in a soil.
The microbial biomass (ATP-content) in the surface 0-5 cm layer was higher than the amount found in the 5-20 cm soil layer (Fig. 3a). the addition of 30 T slurry ha^-1 containing 10 times the normal amount of Sta.-F resulted in a minor decrease in ATP-content (0-5 cm) and an increase (5-20 cm), compared to the manured reference soil. Treatment with Sta.-F and 90 kg slurry ha^-1 was slightly higher than the reference soil in the 5-20 cm layer. Applications of 30 T and 90 T slurry ha-1 (slurry from farm using Sta.-F in the animal building) did not affect the microbial biomass within the same soil depth. The microbial biomass in the plot receiving 450 kg Sta.-F ha^-1 was lowest in the 0-5 cm and 5-20 cm layers. The microbial biomass was slightly higher in treatment receiving 150 kg Sta.-F ha-1 than in the fertilized treatment without Sta.-F within the same depth.
CO₂ evolution (0-5 and 5-20 cm) was lowest in treatments added Sta.-F in 30 T slurry. No effects within 0-5 cm and 5-20 cm depth were observed when 90 T slurry was applied.
 

Dehydrogenase activity showed more or less the same activity for the different field treatments and depths. Specific activity was slightly reduced in the treatments receiving Sta.-F in 30 T slurry and only minor differences were observed for the other treatments.
The ATP content and CO₂ evolution were measured in the deeper soil layers (Fig. 3c). Very low levels were found for the two parameters below the plough layer compared to the similar treatments in the plough layer. At the 50-75 cm depth (30 T slurry), ATP content and CO₂ evolution were highest in treatments containing slurry with Sta.-F. In all the other treatments (50-75 cm) and in the treatments at the 75-100 cm depth, the ATP content was not related to the application of slurry and Sta-F. The CO₂ evolution from the different soil treatments within the same depths was not influenced by Sta.-F.
The overall picture of measurements of microbial biomass and activity at the three sampling events showed that Sta.-F often improved the soil conditions for the microbial life, resulting in a stimulation of the microorganisms. Occasionally Sta.-F caused a temporary inhibition of the microbial biomass and activity. This effect of Sta.-F was not found to such an extent that it was in any way critical for the survival of the microorganisms.
Potential nitrification activity (PNA) was examined in the soil treatments (Fig. 4). Addition of 15 kg Sta.-F in 30 T slurry ha^-1 did not influence the activity of the nitrifying bacteria (both depths). There was a significantly increase of PNA when 150 kg Sta.-F in 30 T slurry ha-1 had been applied at both depths. Adding 90 T slurry ha^-1 with 45 and 450 kg Sta.-F, respectively, reduced PNA in the surface 0-5 cm layer with increasing amounts of Sta.-F as compared to the reference (90 T slurry-0 kg Sta.-F). On the other hand, PNA at the 5-20 cm depth was highest in treatments containing Sta.-F. Therefore it is likely that the inhibition in the surface layer was of a temporary nature due to an accumulation of Sta.-F after two years with ryegrass, where no soil cultivation had taken place.
PNA in treatments added slurry with Sta.-F from animal buildings (30 and 90 T slurry) was higher at 5-20 cm depth than in the surface layer. In the field treatments receiving inorganic fertilizer without and with Sta.-F (150 kg Sta.-F ha^-1), PNA was at the same level (0-5 and 5-20 cm) and slightly lower than after addition of 30 T slurry without Sta.-F. The highest content of Sta.-F (450 kg Sta.-F ha-1) plus inorganic fertilizer increased PNA slightly compared with the reference treatment with inorganic fertilizer only. In all field treatments PNA showed that Sta.-F only influenced the N-mineralization process in a negative direction at the surface when high amounts of slurry and Sta.-F were added (90 T and high amounts of Sta.-F).
 

Sta.-F in 30 T slurry (10 x normal amount), resulted in a positive effect of Sta.-F on PNA. In general, adding Sta.-F to soil did not inhibit PNA.

Chemical parameters measured in slurry

Table 4 shows the chemical properties of the slurry used in 1997 and 1998. Although the dry matter content was higher in slurry from 1997 than 1998, a range of the other parameters measured was very similar for the same slurry type and treatment in the two years (dry matter, pH, tot.-C, tot.-N, C/N-ratio, P and total Cu). The SO₄-S increased in slurry containing Sta.-F. The high content of total Zn originates from pigfeed. Zn is not contained in Sta.-F. The results of the measurements of the Cu content in slurry are discussed on page 16.

Fig. 5. Cu from slurry without and with Sta.-F loaded to the field experiment in 1998. The results are the mean of two replicated samples.

Table 4. Chemical analyses in the slurry used for field experiment

Microbiological parameters measured in slurry

The microorganisms in slurry are mainly anaerobic organisms (oxygen-free) as opposed to the microorganisms in soil which are mainly aerobic organisms (require oxygen). Therefore, the microorganisms in the slurries will die when slurry is added to the soil and together with other organic material these organisms will be an energy source for the microorganisms living in soil. This is the reason why it is also necessary to study the microbial processes in the soil, when an evaluation of different products on the environmental conditions in field soil is performed.
Microbiological parameters were measured in slurries used for the field experiment in 1998. The microbial biomass (ATP content) and AO-stained bacteria were unchanged after sampling in slurry without and with the two different concentrations of Sta.-F (Fig. 6a). After 72 days of incubation at 20^oC, a minor decrease was observed in ATP content and number of bacteria in slurry containing 5 kg Sta.-F T^-1 compared to the slurries without and with 0.5 kg Sta.-F T^-1. The slurry added Sta.-F in the animal building contained a smaller microbial biomass and number of bacteria than that found in the other slurry type (0 and 0.5 kg Sta.-F T^-1). The amount of microorganisms could not be related to differences in the measured chemical analyses in the slurry. It is likely that the presence of easily available carbon compounds for the microorganisms differs in between the two slurry types.
The microbial activity was measured in the slurry under anaerobic conditions (N₂-gas) by CO2 evolution as an expression of mainly the respiration of the microorganisms. CO₂ evolution was at the sampling time lower in slurry with 5 kg Sta.-F T^-1 than in slurry with 0 and 0.5 kg Sta.-F T^-1 (Fig. 6b). As found for the amounts of microorganisms, the slurry added Sta.-F in the animal building had a lower CO₂ evolution than in the other slurry type. After incubation at 20^oC for up to 72 days, the microbial activity gradually decreased in all the slurry treatments and reached a very low activity level.
Dehydrogenase activity is another measure of microbial activity. The results showed the same trends as the CO₂ evolution (Fig. 6b).
It can be concluded that slurry containing St.-F even in very high concentrations (10 times normal amount) does not influence the number and the activity of anaerobic microorganisms in the slurry to an unacceptably low level. Therefore, it is expected that slurry containing St.-F without any problems can be useful for e.g. production of biogas.
 

Fig. 6a. ATP content (microbial biomass) and number of bacteria in slurries used for the Foulum field experiment 1998. The results are the mean of three replicated samples and the bars indicate the standard deviation.
 

Fig. 6b. CO₂-evolution and dehydrogenase activity (microbial activities) in slurries used for the Foulum field experiment 1998. The results are the mean of three replicated samples and the bars indicate the standard deviation.

Yields of ryegrass

In 1997, the first cut of ryegrass was performed on 10 June (Fig. 7a). The yields in field plots added 30 T slurry ha^-1 with normal and 10 times normal amounts of Sta.-F were higher (0.54 and 0.73 T d.w. ha^-1, respectively) than the corresponding treatment adding 30 T slurry ha^-1 without Sta.-F. When 90 T slurry ha^-1 was added the yield was higher than after addition of 30 T slurry ha^-1. However, no effects of Sta.-F were observed at the treatments with the high amounts of slurry. Field treatments added 30 and 90 T slurry with Sta.-F used in animal building gave lower yields than the corresponding field treatment added the other slurry type in equal amounts (30 and 90 T, respectively).
The yields from the sampling dates 24 July and 27 October were very small for all treatments, and there was no effect of Sta.-F. The reason for the low yields for the two last samplings was a shortage of inorganic nitrogen later on during the growth season.
Fig. 7c shows the yields of dry weight as a total of the three cuts. As found for the first sampling event, Sta.-F in 30 T slurry ha-1 increased the crop yields of ryegrass by 0.57 T d.w. ha-1 with normal amount of Sta.-F and 0.82 T d.w. ha-1 for the high addition. The other differences were due to the addition of a higher amount of slurry (90 T slurry ha-1).
In 1998, the highest yields were also found in the first cut taken on 3 June (Fig. 7b). There was an increase of 0.16 T d.w. ha^-1 for treatments containing slurry with normal and high amounts of Sta.-F (30 T slurry ha-1). This was the same pattern as observed in 1997. Inorganic fertilizer added without and with Sta.-F (150 and 450 kg ha^-1 gave the same yields but at a lower level than found in treatments added slurry.
In the second and third cuts (13. July and 24. August 1998), the yields were not influenced by Sta.-F in the slurry. However, there was a small increase of 0.2 to 0.3 T d.w. ha^-1 in treatments receiving Sta.-F and inorganic N directly in the field as compared to the treatment without Sta.-F.
The total yields of the three cuts for 1998 are seen in Fig. 6c. The positive effect of Sta.-F in slurry (30 T slurry ha^-1) on the yields resulted in a surplus of 0.26 and 0.51 T ha-1 for the normal and high amount of Sta.-F, respectively. Furthermore, there was also a positive effect of Sta.-F added together with inorganic N (0.60 T d.w. ha^-1 for both treatments with Sta.-F).
 

Copper content in ryegrass

Cu content in plants expressed as dry weight per unit as an average of the three cuts is shown in Fig. 8. Cu increased in the crop in treatments receiving high amounts of Cu (90 T slurry) and 450 kg Sta.-F ha-1 added directly to the field, indicating that the Cu content in a crop is influenced by the content of Cu present in a soil.
Plant uptake of Cu per ha in the crop (1997 and 1998) is shown in Table 5. In 1997, the three cuts without Sta.-F contained 23 g (30 T slurry) and 47 g Cu ha^-1 (90 T slurry). The corresponding treatments with the highest loading of Sta.-F raised the Cu content by 7 g (30 T) and 2 g Cu (90 T), respectively. It was seen that treatments with the highest amounts of Cu in the soil also resulted also in the highest Cu uptake in plants. In 1998, the three cuts without Sta.-F removed 53 g (30 T slurry) and 94 g Cu ha^-1 (90 T slurry), respectively. The present of Sta.-F (normal and 10 times normal amount) in the treatments increased the Cu uptake with 5 and 13 g Cu for 30 and 90 T slurry, respectively. The Cu uptake was independent of the different amounts of Sta.-F added to the land. The slurry added Sta.-F in the animal building followed the same patterns as found for the Foulum slurry. The ryegrass in the inorganic field treatment without Sta.-F removed 38 g Cu ha-1. Sta.-F loaded directly to the soil also increased the plant uptake of Cu by 6 and 20 g Cu, respectively (150 and 450 kg Sta.-F ha^-1). In the treatments, where Sta.-F has shown to increase the crop yield, the increase in the measured Cu is a combination of a higher crop yield and a higher Cu uptake in plants.
It can be concluded that the three cuts of ryegrass were able to remove up to 57 g Cu ha^-1, dependent on crop yields and Cu concentration in the soil, when 30 T slurry was loaded to the field plots. Slightly higher amounts of Cu were removed in treatments receiving Sta.-F both after adding 30 and 90 T slurry.

Fig. 8. Cu content in ryegrass expressed per kg dry weight. The results are the mean of replicated analyses from each of two replicated plots and three cuts. The bars indicate the standard deviation in between the three cuts.

Table 5. Cu content in ryegrass

Conclusions (in English)

A field experiment was initiated at Research Centre Foulum in 1997. The purpose was to measure possible effects of Stalosan^® F on the chemical and microbiological parameters in soil and in the slurry used for the field experiment. The yields of ryegrass and crop uptake of copper in the crop were also measured. The measurements in the field experiment will be continued for a further two years period with a crop of winterwheat and with similar amounts of slurry and Stalosan^® F. After two years with yearly loading of slurry containing different concentrations of Stalosan^® F, the following results were obtained:

1. Stalosan^® F in slurry even at 10 times the normal applied amount does not reduce the number and the activity of anaerobic microorganisms in the slurry to an unacceptably low level. It is therefore expected that Sta.-F in slurry can be used in e.g. biogas production without any negative effects.

2. Potential nitrification activity (PNA) was examined in the soil with the different additions of slurry and Stalosan^® F (August 1998).
   The addition of a normal amount of Stalosan^® F in 30 T slurry per ha did not affect the activity of the nitrifying bacteria at the 0-5 and 5-20 cm depth. There was a significantly increase of PNA at both 0-5 and 5-20 cm depths, when 10 x the normal amount had been applied.
   Adding 90 T slurry per ha with normal and 10 x normal amounts of Stalosan^® F resulted in a decrease of PNA in the surface soil layer with increasing amounts of Stalosan^® F compared with the reference soil with addition of 90 T slurry per ha and 0 kg Stalosan^® F. However, PNA was not lower than the corresponding treatments receiving Stalosan^® F directly to the soil.
   PNA at the 5-20 cm depth in treatments receiving 90 T slurry per ha and Stalosan^® F increased, showing that the nitrifying bacteria were stimulated by Stalosan^® F below the surface layer. Therefore it is most likely that the inhibition in the surface layer was of a temporary nature, maybe due to an accumulation of residues of Stalosan^® F and slurry after two years with ryegrass, where no soil cultivation took place.

3. The overall picture of measurements of microbial biomass and activity showed that Stalosan^® F, both in slurry and added directly to the soil, often improves soil conditions for microbial life, resulting in a stimulation of the microorganisms. Stalosan^® F added in very high concentrations may sometimes cause a temporary inhibition of the organisms and their activity. However, an inhibition followed by a stimulation of the microorganisms is commonly observed in soils, when high amounts of organic matter were added to the soil. The occasionally observed inhibition was not found to an extend, where it could be critically for the microorganisms.

4. A positive effect was found on the yields of ryegrass in 1997 and 1998 with Sta.-F in 30 T slurry per ha. The surplus yields were 570 and 260 kg dry weight per ha, respectively. This was also the case, when Stalosan^® F was added directly to land together with inorganic N, where an increase of 600 kg dry weight per ha was found in 1998. There could be several explanations for the increased yields. One possibility is improved conditions for the soil microorganisms or an increased content of sulphur in soil originating from Stalosan^® F.

5. By the application of Stalosan^® F in animal housings at the levels suggested by the producer, gives only a moderate increase of copper at about 60 g copper per ha per year. The main part of copper applied to the soil originated from pigfeed for sows and piglets. The copper content in slurry without Stalosan^® F, equivalent to 30 T slurry per ha, was 620 g copper.

6. Most crops are expected to take up 20-50 g copper per ha per year, which is in the order of magnitude of the added copper by Stalosan^®-F. In the Foulum experiment with ryegrass and three cuts, 57 g copper per ha was removed after applying of 30 T slurry per ha in 1998. The amount is dependent on Cu content in the soil and the crop yields.

After two years study of possible effects of the hygiene substance Stalosan^® F on the chemical and microbiological conditions in slurry and in soil, the main conclusion is that the product is very useful and it has no observed harmful effects on the soil environment, when it is used in the amounts suggested by the producer. Occasionally, the product even stimulated the soil microorganisms and raised the yields of ryegrass.

Konklusioner (in Danish)

Et markforsøg ved forskningscenter Foulum blev iværksat i 1997. Formålet var at klarlægge om anvendelse af Stalosan^® F i stalden ville påvirke de kemiske og mikrobiologiske parametre i jorden og i den gylle, der blev anvendt i markforsøget. Høstudbytterne af rajgræs og kobberoptagelse i afgrøderne blev også målt. Undersøgelserne vil blive fortsat i yderligere 2 år med dyrkning af vinterhvede og tilsætning af de samme mængder af gylle og Stalosan^® F. Efter de første 2 års studier med en årlig tilførsel af gylle, der indeholdt forskellige mængder af Stalosan^® F, blev følgende resultater fundet:

1. Stalosan^® F i gylle, selv i mængder på 10 x normal anvendt mængde, påvirkede ikke antallet af mikroorganismerne og deres aktivitet i gyllen i en uacceptabel grad. Derfor skulle gylle med restprodukter fra Sta.-F uden problemer kunne benyttes til f.eks. biogas produktion.

2. Potentiel nitrifikations aktivitet (PNA) blev undersøgt i jorden med de forskellige tilførsler af gylle og Sta.-F.
   Tilførsel af en normal mængde Sta.-F indeholdt i 30 tons gylle/ha, påvirkede ikke de nitrificerende bakteriers aktivitet. Der var en signifikant stigning i PNA i hele pløjelaget, når 10 x den normalt anvendte Sta.-F mængde blev anvendt.
   Tilførsel af 90 tons gylle/ha med normal og 10 x normal mængde Sta.-F, resulterede i et fald i PNA i overfladen med stigende mængder Sta.-F i forhold til referencejorden med 90 tons gylle uden Sta.-F. Imidlertid var denne aktivitet ikke lavere end i forsøgsbehandlingen, der kun fik tilført handelsgødning.
   PNA i 5-20 cm laget var højest i de behandlinger, der havde fået tilført 90 tons gylle pr. ha med Sta.-F. Dette tyder på at disse bakterier stimuleres ved tilstedeværende af Sta.-F. Det er mest sandsynligt, at hæmningen i overfladen af PNA er af midlertidig karakter, og kunne skyldes en ophobning af rester af gylle og Sta.-F efter 2 års afgrøde med rajgræs, hvor der ikke blev foretaget nogen jordbearbejdning.

3. Hovedresultatet af målingerne af den mikrobielle biomasse (mængden af mikroorganismerne) og mikroorganismernes aktivitet viste at Sta.-F, både i gylle og tilført direkte til jorden, ofte forbedrer betingelserne i jorden for mikroorganismerne, idet mængde og aktivitet øges. Sta.-F tilført i meget store mængder kan af og til forårsage en midlertidig hæmning af organismerne og deres aktivitet. Imidlertid er det i jord meget almindelig at finde en mindre hæmning efterfulgt af en stimulering af mikroorganismerne, når store mængder organisk stof tilføres jorden. Den observerede lejlighedsvise hæmning blev aldrig fundet i en udstrækning, hvor anvendelse af Sta.-F var kritisk for mikroorganismerne.

4. Der blev fundet en positiv virkning af Sta.-F på udbytterne af rajgræs ved anvendelse af 30 tons gylle pr. ha med Sta.-F. Merudbyttet p.g.a. Sta.-F var på 570 kg tørstof pr. ha i 1997 og 260 kg tørstof pr. ha i 1998. Virkningen blev også set når Sta.-F blev tilført direkte til marken sammen med handelsgødning. Her blev der fundet et merudbytte på 600 kg tørstof pr. ha. Der kan være flere forklaringer på Sta.-F's betydning for udbyttestigningerne. Det kan skyldes forbedrede forhold for jordbundens mikroorganismer eller en svovlvirkning fra Sta.-F.

5. Ved anvendelse af Sta.-F i staldsystemer med de angivne mængder fra firmaet, sås kun en moderat stigning i kobberindholdet i gyllen, der svarer til en tilførsel til jorden på ca. 60 g kobber pr. ha om året. Hovedparten af kobberet i gyllen stammer fra foderblandinger til søer med smågrise. Gyllen uden Sta.-F tilført med 30 tons gylle pr. ha indeholdt 620 g kobber, som stammer fra foderet.

6. De fleste afgrøder forventes at optage 20-50 g kobber pr. ha om året, som er i samme størrelsesorden som det tilførte kobber med Sta.-F. I markforsøget med rajgræs og tre slæt pr. år, blev der i 1998 optaget 57 g kobber pr. ha efter anvendelse af 30 T gylle pr. ha. Optagelsen af kobber var afhængig af den mængde kobber , som fandtes i jorden i forvejen og høstudbytternes størrelse.

Efter 2 års undersøgelser over en eventuel virkning af hygiejnemidlet Stalosan^® F på kemiske og mikrobiologiske forhold i gylle og i jorden er hovedkonklusionen, at produktet er meget nyttigt og der er ikke observeret skadelige virkninger på jordmiljøet, når det anvendes i de mængder, der er foreskrevet af producenten. Lejlighedsvis gav produktet ligefrem en stimulering af mikroorganismerne i jorden og øgede høstudbytterne af rajgræs.

Schlußfolgerungen (in German)

Das Forschungszentrum Foulum führte 1997/98 einen Feldversuch durch. Der Zweck bestand darin zu klären, ob die Verwendung von Stalosan^® F (Sta.-F) im Stall die chemischen und mikrobiologischen Parameter der mit Sta.-F behandelten Gülle oder des mit dieser Gülle gedüngten Bodens beeinflußt. Gemessen wurden ebenfalls der Ertrag sowie die Kupferaufnahme von Welschem Weidelgras. Die Untersuchungen werden für zwei weitere Jahre mit dem Anbau von Winterweizen unter Zufuhr der gleichen Mengen an Gülle und Sta.-F fortgesetzt. Nach Ablauf der ersten zwei Versuchsjahre und einer jährlichen Ausbringung von Gülle, die unterschiedliche Mengen an Stalosan F enthielt, wurden folgende Ergebnisse festgestellt:

1. Stalosan^® F in der Gülle beeinflußte nicht die Anzahl der Mikroorganismen und deren Aktivität in der Gülle in einem unakzeptablen Maß, selbst bei Verwendung des 10fachen der vorgeschriebenen Dosierung (5 kg Sta-F/Tonne Gülle). Deshalb dürfte Gülle mit Restbeständen von Sta.-F beispielsweise in der Biogas-Produktion problemlos eingesetzt werden können.

2. Der Einfluß von Stalosan F auf die potentielle Nitrifikationsaktivität (PNA) im Boden wurde mittels verschiedener Gaben von Gülle und Sta.-F untersucht.
   Die Zufuhr einer typischen Menge Sta.-F mit 30 Tonnen Gülle/ha beeinflußte nicht die Aktivität der nitrifizierenden Bakterien. Bei einer Zufuhr des 10fachen der Normaldosierung von Sta.-F ließ sich im gesamten Pflughorizont eine signifikante PNA-Erhöhung nachweisen.
   Die Ausbringung von 90 Tonnen Gülle/ha mit der normalen und der 10fachen Dosierung von Sta.-F hatte einen Rückgang der PNA in der obersten Bodenschicht (0-5 cm) mit zunehmender Sta.-F Konzentration zur Folge im Vergleich zur Sta.-F freien Kontrolle mit 90 Tonnen Gülle/ha. Diese PNA war jedoch nicht niedriger als in der Behandlung, bei der nur handelsüblicher Dünger zum Einsatz kam.
   Die PNA in der 5-20 cm Bodenschicht war bei den Behandlungen am höchsten, die eine Zufuhr von 90 Tonnen Gülle/ha mit Sta.-F erhalten hatten. Das deutete auf eine stimulierende Wirkung von Sta.-F für die Bakterienflora dieser Bodenschicht hin. Es ist daher wahrscheinlich, daß die Hemmung der PNA in der obersten Schicht (0-5 cm) einen zeitweiligen Charakter hatte und durch eine Akkumulation von Gülle- und Sta.-F-Resten nach zweijährigem Grasanbau ohne Bodenbearbeitung verursacht wurde.

3. Das Hauptergebnis der Messungen der mikrobieller Biomasse (Menge der Mikroorganismen) und ihrer Aktivität im Boden war eine häufig beobachtete Verbesserung der Bedingungen für Bodenmikroorganismen durch Sta.-F in der Gülle und auch nach direkter Einbringung von Sta.-F in den Boden, die sich in größerer Biomasse und erhöhter Aktivität äußerte. Wird Sta.-F allerdings in sehr großen Mengen zugeführt, kann das mitunter eine zeitweilige Hemmung der Mikroorganismen und ihrer Aktivität zur Folge haben. Häufig ließ sich im Boden eine geringe Hemmung der mikrobiellen Aktivität, gefolgt von einer Zunahme, beobachten, wenn dem Boden große Mengen an organischer Substanz zugeführt wurden. Die gelegentliche Hemmung wurde nie in einem Ausmaß festgestellt, bei dem die Anvendung von Sta.-F kritisch für die Mikroflora war.

4. Beim Einsatz von 30 Tonnen Gülle/ha mit Stalosan F wurde eine positive Wirkung von Sta.-F auf den Weidelgrasertrag festgestellt. Der durch den Einsatz von Sta.-F erzielte Mehrertrag machte 1997 570 kg Trockenmasse/ha und 1998 260 kg Trockenmasse/ha aus. Eine positive Wirkung wurde auch festgestellt, wenn Sta.-F zusammen mit handelsüblichem Dünger ausgebracht wurde. Dabei wurde ein Mehrertrag von 600 kg Trockenmasse/ha im Vergleich zur Behandlung mit handelsüblichem Dünger ohne den Zusatz von Stalosan F verzeichnet. Die Bedeutung von Sta.-F dür die Ertragssteigerungen kann mehrere Erklärungen haben. Ein Grund können verbesserte Bedingungen für die Mikroorganismen im Boden, ein anderer die‚ Schwefelwirkung' von Sta.-F sein.

5. In Stallsystemen, in denen Stalosan F in den vom Hersteller angegebenen Mengen verwendet wurde, ist in der Gülle nur eine mäßige Erhöhung des Kupfergehaltes fastgestellt worden, die einer Bodenzufuhr von ca. 60 g Cu/ha/Jahr entspricht. Der Hauptanteil an Kupfer in Gülle stammt aus Futtermischungen für Sauen mit Ferkeln. Dreißig Tonnen Gülle ohne Sta.-F enthielten 620 g Kupfer, das aus dem Futter stammt.

6. Die meisten Feldfrüchte nehmen erwartungsgemäß 20-50 g Cu/ha/Jahr auf, was der Größenordnung des mit Sta.-F zugeführten Kupfers entspricht. Im Feldversuch mit Welschem Weidelgras (3 Schnitte/Jahr) wurden 1998 bei der Ausbrinung von 30 Tonnen Gülle/ha 57 g Kupfer/Jahr aufgenommen. Die Gesamtkupferaufnahme war dabei von dem anfänglichen Kupfergehalt des Bodens und der Ertragsmenge abhängig.

Nach zweijährigen Untersuchungen einer mögliche Nebenwirkung von Stalosan^® F auf chemische und mikrobiologische Prozesse in Gülle und im Boden ergibt sich die Schlußfolgerung, daß Stalosan^® F ein sehr nützliches Produkt ist. Bei der Verwendung von Mengen, wie sie vom Hersteller vorgeschrieben werden, wurden keine schädlichen Wirkungen auf die mikrobiologischen und chemischen Verhältnisse im Boden festgestellt. Gelegentlich hatte Stalosan^® F sogar eine stimulierende Wirkung auf die Bodenmikroflora und erhöhte die Erträge von Weidelgras.

Conclusiones (in Spanish)

En 1997, se inició un ensayo de campo en el Centro de Investigaciones de Foulum. El objetivo era aclarar si la aplicación de StalosanÒ F en los establos, influía en los parámetros químicos y microbiológicos del suelo y del purín que se aplicaba para el ensayo de campo. Se midieron también los rendimientos de la cosecha de raygrass y el cobre absorbido por los cultivos. Las investigaciones continuarán otros 2 años con cultivos de trigo blanquillo y la aplicación de las mismas cantidades de purín y StalosanÒ F. Después de los primeros 2 años de investigación, con una incorporación anual de purín que contenía diferentes cantidades de StalosanÒ F, se obtuvieron los siguientes resultados:

1. StalosanÒ F en purín; ni las cantidades 10 veces más grandes que la normal, influían de modo no aceptable en el número de microorganismos, ni en su actividad en el purín. Por ello, el purín con productos residuales de Sta.-F, puede utilizarse, sin problema alguno, en la producción de biogás, etc.

2. La actividad de nitrificación potencial (ANP) fue examinada en la tierra con las diferentes aplicaciones de purín y Sta.-F.
   La aplicación de una cantidad normal de Sta.-F, contenida en 30 toneladas de purín/ha., no influía en la actividad de las bacterias nitrificantes. Fue observado un aumento significativo de la ANP en toda la capa arable, cuando se utilizaban cantidades 10 veces más grandes que la cantidad normal de Sta.-F.
   La aplicación de 90 toneladas de purín/ha. con una cantidad normal de Sta.-F o con cantidades 10 veces más grandes que la cantidad normal, significaba una pérdida en la ANP, en la superficie, con cantidades crecientes de Sta.-F, en comparación con el suelo de referencia con 90 toneladas de purín sin Sta.-F. Sin embargo, esta actividad no era inferior a la de la explotación de ensayo, que había incorporado exclusivamente abono industrial comercial.
   La ANP en la capa de 5 a 20 era mayor en las explotaciones que habían incorporado 90 toneladas de purín/ha. con Sta.-F. Esto significa que estas bacterias son estimuladas por la presencia de Sta.-F. Lo más probable es que la inhibición de la ANP en la superficie tiene un carácter provisional y se debe exclusivamente a una acumulación de los residuos de purín y Sta.-F, después de 2 años con cultivo de raygrass, sin laboreo del suelo.

3. El resultado principal de las mediciones de la biomasa microbiana (la cantidad de los microorganismos) y la actividad de los microorganismos, demuestra que Sta.-F, tanto en el purín como aplicado directamente a las tierras, en muchos casos mejora las condiciones de los microorganismos en ellas, ya que aumenta su cantidad y su actividad. Sta.-F, en grandes cantidades, puede ocasionar a veces una inhibición provisional de los organismos y de su actividad. Sin embargo, es común encontrar en la tierra una inhibición menor, seguida por una estimulación de los microorganismos cuando se aplican grandes cantidades de materia orgánica a las tierras. La inhibición periódica observada, nunca fue de tal envergadura que la utilización de Sta.-F llegara a ser crítica para los microorganismos.

4. Se comprobó un efecto positivo del Sta.-F sobre las cosechas de raygrass, al aplicar 30 toneladas de purín/ha. con Sta.-F. El sobrerrendimiento debido al Sta.-F, fue de 570 kg. de materia seca/ha. en 1997 y de 260 kg. en 1998. El mismo efecto se produjo cuando Sta.-F fue aplicado directamente a las tierras junto con abono industrial comercial. Aquí se comprobó un sobrerrendimiento de 600 kg. de materia seca/ha. La importancia del Sta.-F para las mejoras del rendimiento tiene varias explicaciones. Puede ser que haya mejorado las condiciones de los microorganismos del suelo o que se trate de un efecto sulfuroso del Sta.-F.

5. En la aplicación de Sta.-F en los sistemas de establo y en las cantidades indicadas por la firma, se comprobó solamente un moderado aumento del contenido de cobre en el purín, que corresponde a una incorporación anual a la tierra de aprox. 60 g de cobre/ha. La mayor parte del cobre del purín, proviene de los piensos compuestos para cerdas con lechones. El purín sin Sta.-F., aplicado en cantidades de 30 toneladas de purín/ha., contenía 620 g de cobre, proveniente del pienso.

6. Se estima que la mayor parte de los cultivos absorberá de 20 a 50 g de cobre/ha. por año, lo que corresponde a la magnitud del cobre alimentado con Sta.-F. En el ensayo de campo con raygrass y tres siegas por año, cada ha. absorbió, en 1998, 57 g de cobre posteriormente a la aplicación de 30 toneladas de purín/ha. La absorción de cobre dependía de la cantidad de cobre que ya había en la tierra y de los rendimientos de la cosecha.

Después de 2 años de investigación de un posible efecto del agente de higiene StalosanÒ F, sobre las condiciones químicas y microbiológicas en el purín y en las tierras, la conclusión principal es que el producto es muy útil y que no se han observado efectos adversos en el medio terrestre cuando se dosifica en las cantidades recomendadas por el fabricante. En algunos casos, el producto representaba directamente un estímulo de los microorganismos del suelo y un aumento de los rendimientos de la cosecha de raygrass.

Conclusions (In French)

Une expérience plein champ fut initiée en 1997 au centre de recherche de Foulum. Elle devait permettre de savoir si la mise en oeuvre de Stalosan^® F dans les étables influençait ou non les paramètres chimiques et microbiologiques du sol et du lisier utilisé lors de l'expérimentation. Furent également mesurés le rendement des récoltes de ray-grass et les quantités de cuivre absorbées par les récoltes. Cette expérience devait être poursuivie durant deux ans avec une culture de blé d'hiver et le recours aux mêmes quantités de lisier et de Stalosan^® F. Après les deux premières années d'études qui virent l'épandage annuel de lisier renfermant des quantités variables de Stalosan^® F, on arriva aux résultats suivants :

1. La présence de Stalosan^® F dans le lisier dans des concentrations pouvant même atteindre 10 fois la quantité normalement mise en oeuvre n'influence pas de manière inacceptable le nombre de micro-organismes et leur activité dans le lisier. Il semble donc que le lisier chargé de résidus de Sta.-F puisse sans crainte servir à produire du biogaz par exemple.

2. L'activité de nitrification potentielle (ANP) du sol fut analysée en fonction des diverses doses de lisier et de Sta.-F.
   L'apport d'une quantité normale de Sta.-F dans 30 tonnes de lisier à l'hectare n'exerce aucune influence sur l'activité des nitrobactéries. Une augmentation sensible de l'ANP fut enregistrée dans toute la couche labourable en présence d'une dose de Sta.-F 10 fois supérieure à la normale.
   L'épandage de 90 tonnes de lisier à l'hectare et l'utilisation de Sta.-F dans des concentrations normale et 10 fois supérieure à la dose prescrite entraînèrent, si l'on se réfère au témoin amendé avec 90 tonnes de lisier exempt de Sta.-F, une diminution de l'ANP en surface, proportionnelle aux quantités de Sta.-F mises en oeuvre. Toutefois, cette activité n'était pas inférieure à celle enregistrée lors du traitement expérimental qui vit l'utilisation d'un fertilisant du commerce.
   L'ANP dans les couches 5 à 20 était maximale dans les cas où l'on avait épandu 90 tonnes de lisier à l'hectare et additionné du Sta.-F. Il semble donc que la présence de Sta.-F stimule ces bactéries. Tout porte cependant à croire que l'inhibition de l'ANP en surface revêt un caractère passager. Elle pourrait s'expliquer par une accumulation des résidus de lisier et de Sta.-F après 2 campagnes de ray-grass et l'absence de toute préparation du sol.

3. Les principaux enseignements des mesures effectuées sur la biomasse microbienne (quantités de micro-organismes) et sur l'activité des micro-organismes montrent que le Sta.-F, qu'il soit dans le lisier ou directement incorporé dans le sol, améliore souvent les conditions que les micro-organismes trouvent dans le sol car le nombre et leur activité augmentent. Il peut arriver que l'apport de Sta.-F en très grande quantité inhibe momentanément le développement et l'activité des micro-organismes. Il est cependant très habituel de constater en la matière une inhibition relative des micro-organismes, directement suivie d'une stimulation, quand une dose importante de matière organique est incorporée dans le sol. L'inhibition occasionnelle observée suite à la mise en oeuvre de Sta.-F n'a jamais atteint un niveau critique pour les micro-organismes.

4. Un effet favorable du Sta.-F sur les récoltes de ray-grass fut mis en évidence en présence de 30 tonnes de lisier par hectare additionnées de Sta.-F. Le Sta.-F a permis d'augmenter les récoltes de 570 kg de matière sèche à l'hectare en 1997 et de 260 kg en 1998. Un effet comparable fut constaté quand le Sta.-F fut directement utilisé sur le champ en association avec un fertilisant du commerce. Le supplément de récolte fut, dans ce cas, estimé à 600 kg de matière sèche par hectare. Cet effet du Sta.-F sur les rendements peut s'expliquer de plusieurs manières : par une amélioration des conditions de développement des micro-organismes du sol ou par l'apport de soufre dû au Sta.-F.

5. La mise en oeuvre, dans les systèmes de stabulation, de Sta.-F dans les quantités indiquées par la société ne semble qu'entraîner une augmentation modérée de la teneur en cuivre dans le lisier, correspondant à un apport de 60 g env. de cuivre par hectare et par an dans le sol. La majeure partie du cuivre présent dans le lisier provient des soupes destinées aux truies et aux porcelets. Les 30 tonnes de lisier par hectare, exemptes de Sta.-F, renfermaient 620 g de cuivre qui venait du fourrage.

6. On pense que la plupart des récoltes absorberont 20 à 50 g de cuivre par hectare et par an, soit une quantité similaire à l'apport de cuivre imputable au Sta.-F. L'expérimentation plein champ faite avec du ray-grass et trois fauchages par an montre qu'en 1998, la quantité de cuivre absorbée est de 57 g/ha en épandant 30 tonnes de lisier à l'hectare. L'absorption de cuivre dépendait de la quantité de cuivre déjà présente dans le sol et de l'importance des rendements.

Deux ans d'études sur l'incidence éventuelle du produit hygiénique Stalosan^® F sur les paramètres chimiques et microbiologiques du sol et du lisier permettent avant tout de conclure que ce produit est très utile et qu'aucune toxicité n'a été observée sur le sol si le produit est utilisé dans les doses prescrites par le fabricant. Dans certains cas, ce produit a même stimulé les micro-organismes du sol et permis d'augmenter les rendements de ray-grass.

Acknowledgements

I wish to thank Director, M.Sc. Niels van Wyhe, Stormøllen A/S, for inspiration and ideas to initiate this project. Bodil Möllnitz, Jørgen Mogensen and Benjamin Galacho are gratefully acknowledged for their skilful technical assistance and Lic. Agro. Kristian Smedegaard and M.Sc. Carl Gustav Holst for valuable advice and discussions. The farmers Carlo Nielsen and Kristian Hartwigsen kindly supported Research Centre Foulum with slurry. The project was financed by Stormøllen A/S.

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