Effect of integrated nutrient management on productivity and soil health in pigeonpea (Cajanus cajan)-wheat (Triticum aestivum) cropping system

A field experiment was conducted during 2004–07 at the research farm of IARI, New Delhi, to study the nutrient management strategies for pigeonpea [Cajanus cajan (L) Millsp]-wheat [Triticum aestivum (L.) emend. Fiori & Paol.] and its effect on soil health. The sandy loam Typic Haplustept soil of the experimental field was well drained, mildly alkaline and non-saline with medium soil fertility status. In pigeonpea, application of fertilizer NPK at soil-test based recommended rates produced 1.44 t/ha grain yield which was significantly higher as compared with unfertilized control. The highest grain yield (1.79 t/ha) was recorded with NPK+FYM (2.5 tonnes/ha). In wheat crop also, integrated use of NPK and FYM (7.5 tonnes/ha) gave significantly higher grain yield (5.23 t/ha) as compared with general recommended dose of NPK (4.28 t/ha). Conjoint use of fertilizer NPK and FYM, improved soil physical health as revealed by a significant decrease in soil bulk density (BD) and an increase in water holding capacity (WHC) vis-à-vis sole fertilizer treatments or unfertilized control during the years of experimentation. Soil BD decreased from 1.50 Mg/m³ in NPK to 1.40 Mg/m³ in NPK + FYM + ID plots. Water holding capacity increased from 35.1% in NPK to 39.4% in NPK + FYM plots. Among biological parameters of soil health, microbial biomass C (MBC), microbial biomass N (MBN) and dehydrogenase activity (DHA) were measured, which varied from 178 to 373 mg/kg, 22.8 to 65.8 mg/kg and 43.7 to 61.0 μg TPF/24 h/g of soil, respectively in different treatments. In general, highest values of these parameters were recorded in treatments that received NPK + FYM with or without ID.