This study aimed to quantify the effects of contrasting composted methods of solid cattle manure (SCM) ondry matter (DM) yield and crop apparent N recovery (ANR)following manure application to maize land. Fresh SCM was stored as stockpiled, roofed, covered and composted heaps. After storage, the manures were incorporated in a sandy soil, and maize ANR both as a proportion of field applied N (ANRF) and collected N from the barn (ANRB),and DM yield was established at three successive growth stages: end of juvenile phase, start of grain filling, and physiological maturity.
During the storage period, on average 6% of the initial Ntotal was lost from covered, whereas this fraction was 12, 21 and 33% from roofed, stockpiled, and composted heaps, respectively. DM yield of maize increased with the application of all the manure types as compared to the unfertilized control, at the end of Juvenile (2.2 vs. 3.1-3.4 Mg ha-1), grain filling (11.2 vs. 13.6-16.4 Mg ha-1) and physiological maturity stages (13.9 vs. 15.3-15.9 Mg ha-1). At a given growth stage, the greatest value was obtained from covered than roofed, stockpiled and composted manures.Maize ANRF was the highest at start of grain filling (20, 29, 31, and 39% of the applied N for composted, stockpiled, roofed and covered treatments, respectively) but lower values were obtained at physiological maturity (12-21%). The respective values in case of maize ANRB were 13, 23, 27 and 37% of total N taken from barn at the start of grain filling while it was also lower (8-20%) at physiological maturity. It is concluded thatstorage of SCM under an impermeable plastic cover reduce N losses, increased DM yield and ANR thereby improves on-farm N cycling as compared to traditional stockpiling or composting.