Farm yard manure application mitigates aluminium toxicity and phosphorus deficiency for different upland rice genotypes

Abstract

AbstractUpland rice production on acid, weathered soils is often constrained by phosphorus (P) deficiency and aluminium toxicity. Farmyard manure application (FYM) can sharply enhance yields and agronomic P fertilizer (TSP) efficiency under such abiotic stresses. We tested the hypothesis that rice genotypes differ in aluminium tolerance and in the extent of using organic P, offering distinct benefits under TSP‐FYM combinations. Multiple field trials were conducted in the uplands of Madagascar, with factorial combinations of six genotypes, amendments of FYM (at a rate of 17–25 kg P ha−1 vs. a zero control) and TSP application (40 kg P ha−1 vs. a zero control), with blanket N&K additions. Rice grain yields reached a maximum of 6 t/ha after three years of TSP + FYM application, with an average of 3.2 t/ha over the years. Grain yields were about 1.2 t/ha for FYM only and about 1.5 t/ha for TSP only while crops failed under zero P input. Genotypic effects on rice yields were much smaller than the large effects of FYM, TSP or its combination. Application of FYM increased soil pH and CaCl2‐extractable P while decreasing CaCl2‐extractable aluminium. An additional liming trial indicated that the beneficial effects of FYM over TSP relate to liming effects. The FYM application lowers aluminium toxicity which overrules potential effects of organic P supply. Hence, genotypic ranking of yields and agronomic efficiency was inconsistent, without superior genotypes under FYM vs. TSP. However, Chomrong Dhan and FOFIFA 172 generally displayed superior yields. Chomrong Dhan is found to be more sensitive to aluminium toxicity whereas FOFIFA 172 is less performant under low P input. Aluminium tolerance should be considered when developing rice genotypes for high P efficiency in weathered soils.