Soil properties and their relationships with crop productivity after 30 years of different fertilization in the Indian Himalayas

Abstract

We analyzed results of a long-term (30 year) experiment under rainfed soybean-wheat rotation to determine the effects of differences in fertilization on selected soil properties and to investigate the relationship between these properties with crop yield. The results showed that addition of farmyard manure (FYM) with N or NPK fertilizers increased soil organic carbon (SOC) content. FYM application reduced bulk density. Mean weight diameter (MWD), plant available water capacity (PAWC) and water transmission characteristics of soil were highest in the NPK + FYM treatment and lowest in the unfertilized treatments, with the mineral fertilizer treatments showing intermediate results. Combined use of NPK and FYM increased total soil N, Olsen-P, exchangeable Ca2+ and exchangeable Mg2+ by ∼31, 13, 40 and 94%, respectively, in the 0–15 cm soil layer compared to application of NPK. Mean productivity of soybean-wheat system was positively correlated with total SOC stock, TSN stock, Ca2+, Mg2+, NH4OAc-K, MWD, PAWC, and dehydrogenase activity, and negatively related with soil bulk density. Thus, the changes in soil physical and biological properties should also be considered along with soil chemical properties/nutrient status to construe yield sustainability of other long-term field experimental data.