Influence of long-term use of farmyard manure and inorganic fertilizers on nutrient availabiIity in a Typic Ustochrept

Abstract

An experiment was conducted since 1971 to study the effect of long-tern1 use of organic manures and inorganic fertilizers on yield, N mineralization and various physico-chemical properties of soils at Punjab Agricultural University, Ludhiana. Incorporation of organic and inorganic fertilizers gave significantly higher wheat yields (1.64 to 5.73 tonnest ha) than the control. The application of 150% NPK increased the grain yield ofnheat significantly over that of 100% NPK treatment by 0.38 tonnetha. Continous addition of inorganic fertilizers and resulted in decrease in soil pH. Continuous growing of maize (Zea nrays L.,kwheat (Triticum aesfivum L. emend Fiori & Pao1.)-cowpea (Vigrla ztr~guiczclata( L.) Walp) cropping sequence over the years with the use of inorganic fertilizers and farmyard manure markedly increased organic carbon content of soil over the control. The application of farmyard manure with optimum inorganic fertilizers increased the available N content of the soil significantly. There was a considerable build up of available P status (38.7 kg/ ha) with application of higher doese of phosphorus. Available K content also improved and maximum amount was noticed where farmyard manure was added with inorganic fertilizers. micronutrient availability also increased with the continuous use of fertilizers. Maximum availability was observed again where farmyard manure was added with inorganic fertilizers. Correlation and regression analysis indicated that the mineral N and available N influence the applied N behaviour in the long-term fertilizer experiment soils.