Nutrient accumulation and nitrate leaching under broiler litter amended corn fields

Alabama's broiler chicken (Gallus gallus) industry produces large amounts of waste, which are disposed of by application to crop and pasture land. Land application of litter (manure and bedding) from broiler production can lead to contamination from losses of nutrients accumulated in soil. A study was conducted on 2 and 4% slopes from 1991 to 1993 at Belle Mina, Alabama, to determine the effects of broiler litter (BL) on soil elemental concentrations and nitrate leaching under a corn (Zea mays L.)- winter rye (Secale cereale L.) cropping system amended with either: 1) 9 mg.ha-1 of BL, 2) 18 mg.ha-1 of BL, or 3) commercial fertilizer (F) at a recommended rate. Soil was sampled to 100 cm prior to corn planting and subsequent to corn harvest. Soil leachate samples were collected biweekly with wick lysimeters installed at a depth of 100 cm. Litter applications increased concentrations of soil organic carbon (C), extractable phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu) and zinc (Zn). Post harvest soil sampling indicated leaching of soil nitrate that was generally highest under BL18. Soil electrical conductivity measurements were highest under BL18, but values were not in the range considered detrimental to crops. Nitrate-N (NO3-N) concentrations measured in soil percolate at 1-m depth on the 2% slope were higher under F than litter treatments. Both the F and BL18 treatments produced some NO3-N concentrations above the primary drinking water standard but averaged only 8.3 and 4.8 mg.L-1, respectively. The BL9 treatment consistently remained under 10 mg NO3-N.L-1 with a mean concentration of 1.3 mg .L-1. Overall, litter applied a 9 mg.ha-1 produced agronomic results comparable to F and appeared to be the optimal rate of application under the conditions of this study.