Abstract
Comparative study was performed to estimate and compare the recovery rates of N, S and P in added organic matter or chemical fertilizer source in a greenhouse experiment. Fermented poultry manure, cattle manure compost and root residue of Italian ryegrass (Lolium multiflorum L. cv. Waseyutaka) were used as the organic matter source, while ammonium nitrate, potassium phosphate and potassium sulfate served as chemical source for N, S and P respectively. Treatments consisted of two soil types (regosols and andosols), three kinds of organic matter sources. chemical fertilizer source in a factorial experiment. Wagner pots of size (1/5,000 a) were filled with soil and organic matter or equivalent chemical contents provided as fertilizer and the control which contained soil and other mineral nutrients, except for the element under investigation. Depending on the source, the concentrations of N, S, P and C/N ratio of organic matter varied considerably. African millet (Eleusine coracana G_<AERTN>, Snow Brand) was used as an estimate of the mineral recovery. 1) The recovery rates of N and S in added organic matter, especially in root residue which had high C/N ratio were extremely lower than those of the chemical fertilizer. Furthermore it was observed that application of organic matter with a high C/N ratio, such as root residue may result in N and S deficiency in grasses. 2) Generally, the recovery rates of P in organic manure application, especially poultry manure, were higher than that of chemical fertilizer. This was more pronounced in the andosols which have low pH and high phosphate absorption coefficient.
