Impact of dairy manure addition on soil nutrients in northeast and Impact of dairy manure addition on soil nutrients in northeast and south central Kansas south central Kansas

Sixty four percent of the fields (14 of 22) in northeast and south central Kansas would be able to apply dairy manure on a nitrogen basis if the current swine manure application regulations were adopted. Due to high phosphorus levels in some fields, two of the 11 fields in northeast Kansas could not have any manure applied to them. Two other fields in northeast and four fields in south central Kansas would have to limit manure application rates to annual phosphorus required by the crops. Our results indicate minimal accumulation of nitrogen and potassium in the soil profile


Introduction
Nutr ients are recycled to t he land dur ing manure application.Best Management Practice (BMP's) require laboratory analysis of the manure nutrients and soil sampling.Many produc ers utilize results fr om so il sampling and analysis to determine application rates for commercial fertilizers.Manure may be applied to the land after application of fertilizers withou t considerat ion of the potential to accumulate nutrients in the soil pro file.Kansas regulates the quantit ies and amounts of swine manure that may be applied to fields.The application rates are based on yearly soil tests.The objective of this study was to d eter mine the nutrient content in soil profiles that receive dairy manure and to determine the impact of the swine reg ulat ions if they were applied t o the dairy industry.

Study Procedures
Eleven fields from seve n dair ies in nort heast Kansas and 11 fields from five da iries in south central Kansas were selected for this study.The fields receiving manure in northeast Kansas were predominately clay soils.Those in south central region were sandy soils.Soil samples were collected randomly throughout the fields.At least 10 soil samples were collected from each field.Samples from each field were thoroughly mixed and composite samples were sent to t he Kansas State Universit y (KSU) S oils Lab.Soil cores were collected at 0 to 6 inches and 6 to 24 inches.Samples were analyzed for phosphorus, potassium, ammonium and nitrat e.The availa ble nitrogen per acre was estimated using an agronomic equation.

Results
Figure 1 shows the soil phosphorus (P) concentrations at 0 to 6 inch and 6 to 24 inch depths from fields located in northeast Kansas.The P concentrations ranged from 15 to 345 ppm in the top 6 inches.Fields 2W and 4E exceeded 150 ppm in the top 6 inches.Using the swine regulations, no manure could be applied to these fields because the P level exceeded 100 ppm.Fields 4W and 9W could have manure applied based on t he crop P use rate rather than nitrogen.Manure applications to seven of the 11 (64%) fields could still be based on crop nitrogen use.Soil P levels from 6 to 24 inches ranged from 0 to 31 ppm.Again, fields 2W and 4E had the highest P concentrations at 31 and 20 ppm, respectively.Potassium (K) concentrations ranged from 197 to 475 ppm, except field 2W (1,256), for the top 6 inches (Figure 2).At soil depths of 6 to 24 inches, K concentrations ranged from 142 to 347 ppm, except 4E (962).With the exception of these two fields, de cre ases in K from 0 to 6 inches and soil d ept hs of 6 to 24 inches appe are d fair ly consistent.
Figures 3 and 4 show the ammonium and nitrate concentrations in the soil profile.Ammonium concentrations from 0 to 6 inches varied from 3.5-8.5 ppm and reduced to 1.4 to 3.6 ppm at soil depths of 6 to 24 inches (Figure 3).Nitrate concentrations in five fields ranged from 5-10.2 ppm in the top 6 inches.The remaining fields had nitrate concentrations ranging from 22.5 to 76 p pm.The 6 to 24 inch samples showed a similar patt ern.The five fields with lower levels in the upp er p rofile have nitrat e concentrations of from 0.6 to 5.9 ppm in the deeper profile.The other six samples varied from 11.5 to 24. 1 pp m.
Figure 5 shows an estimate of the nitrate availa ble on a per field basis in northeast Kansas.Nitrate concentrations in the so il profile from 0 to 24 inches exceeded 150 lb/acre on five of the 11 fields.
Figure 6 shows the soil phosphorus (P) concentrations at 0 to 6 inches and 6 to 24 inches from fields located in south central Kansas.The P concentrations ranged from 15 to 76 p pm in the top 6 inches.No fields had P concentrations high enough to limit application of manure using the swine regulations.Fields 4E, 5N, 7E and 7S could have manure applied based on the crop P usage rate rather than nitrogen.Manure applications to seve n of t he 11 (64 %) fields could still be based on crop nitrogen usage.Soil P concentrations from 6 to 24 inches were less than 20 ppm.Potassium (K) concentrations ranged from 105 to 350 ppm for the top 6 inches (Figure 7).At soil depths o f 6 to 24 inches, K concentrations ranged from 100 to 190 ppm.With the exception of three fields, decreases in K fro m 0 to 6 inches to soil depths of 6 to 24 inc hes a ppe are d fair ly consistent.
Figures 8 and 9 show the ammonium and nitrate concentrations, respect ively, in the soil profile.The ammonium levels from 0 to 6 inches varied from 2.8-14.2ppm and reduced to 1.5 to 8.6 ppm at soil depths of 6 to 24 inches (Figure 8).Nitrate co ncentr ations in the fields ranged from 7.5 to 25 ppm in the top 6 inches.The results indicate leaching of nitrates in some fields such as 7E, 7S, 7N and 4E.
Figure 10 shows an est imate of t he nitrate available on a per field basis in south central Kansas.Nitrate concentrations in the 24 inch soil profile exceed 100 lb/acre on two of the 11 fields.

Conclusions
In south central Kansas, no fields receiving manure showed high concent rat ions o f P and nitr ate (N O3-N) in the soil p rofile (0 to 24 inches).The K concentrations varied depending on the depth in these fields.None of the farms appear to have fields with excess nutrients.In northeast Kansas, two fields showed high concentrations o f P and nitrate (NO3-N) in the soil profile (0 to 24 inches).The K concentrations varied depending on t he de pth in these fields.Only one of t he far ms see ms to have soils with excess nutrients.Data from this preliminary study suggest that 64 % of the fields where dairy manure is applied would be in compliance with the current swine regulations.Manu re a pplication r ates o n six field s wo uld need to be adjusted to meet the crop phosphorus requirements.
Figure 1.Soil Phosphorus Concentrations from Fields in Northeast Kansas Receiving Dairy Manure.