Tillage, cover cropping, and poultry litter effects on selected soil chemical properties

Abstract

Conservation tillage systems such as no-till with winter rye cover cropping change soil chemical properties, which affect crop growth and the environment. The objectives of this study were to investigate the effect of no-till and mulch-till systems, surface application of poultry litter, and winter rye ( Secale cereale L.) cover crop on soil pH, soil organic matter (SOM), and N and P concentrations in cotton ( Gossypium hirsutum L.) plots. The study was done on a Decatur silt loam in north Alabama from 1996 to 1998. SOM under no-till and mulch-till systems in the 0–15 cm soil depth in November 1998 was 22 g kg −1 ( P<0.05) compared with 15 g kg −1 in November 1996. A similar result was obtained with winter rye cover cropping compared with cotton–winter fallow system. Surface application of poultry litter at 100 or 200 kg N ha −1 increased SOM by 55–80%. In the 200 kg N ha −1 poultry litter treatment, NH 4 in the 30–90 cm soil depth in November 1998 was 22% higher than that in November 1996. Compared with the ammonium nitrate, the poultry litter treatment plots had up to 40% more NO 3 in the 0–30 cm soil depth after the first year of study. Extractable P and soil pH at the end of the study were similar to those at the beginning. This study shows that no-till and mulch-till, winter rye cover cropping, and surface application of poultry litter in cotton production systems can rapidly increase surface SOM. The increase in SOM was attributed to less biological oxidation of crop residues and from soil C contributed by poultry litter. Crop uptake of N and P prevented a significant build up of these nutrients. These results are important to production systems in the US cotton belt where soil productivity is threatened by erosion because of low SOM levels and the safe disposal of poultry litter is becoming a major environmental problem.