Department of Plant Sciences

Long-term field studies are important to generate information on nutrients dynamics which help in understanding nutrients management strategies for sustainable crop productivity. Keeping this in view, the present investigation (2002-07) was carried out in an on-going long term field experiment (started in 1980) to evaluate the effect of continuous cropping on changes in crop productivity, nutrient budget and soil properties with (F1) and without farmyard manure (FYM, F0) under pearl millet- mustard-cowpea (Fodder) cropping sequence. The FYM was applied at 10 t ha-1 once in a year to the kharif pearl millet (F1). Different fertility levels were applied to both FYM treatments: 0 (control, FL0), 50% (FL1), 100% (FL2), and 150% (FL3) of the recommended dose of NP fertilizers (RDF).

The FYM and fertilizer (NP) application increased crops yield over control; however, there was a continuous decline in the productivity of the crops over the years. The overall productivity of pearl millet and mustard grain decreased by 66 and 38%, respectively, in five years over the corresponding yields of 26 and 13.8 q ha-1 in 2002-03 without FYM. A similar decline in crops productivity was also noticed under FL treatments as well as in the control. The inorganic and organic N and P fractions showed depletion over the time in control only. In case of K, all the K fractions showed depletion irrespective of the treatments over the years. The depletion in total K was by 11 and 15 per cent in control and FL2, respectively during five years of cropping over their corresponding content of 7199 and 7964 mg kg-1 in 2002-03. The alone NP fertilization without FYM showed more adverse effect on availability of K, S and micronutrients viz., Zn, Fe and Mn than with FYM treatments.

The study suggested that supplementation of limiting nutrients to provide balanced nutrition to the crops is essential for sustainable higher productivity under intensive cropping on low to medium fertility light textured soils. The use of FYM and inclusion of leguminous crop like cowpea (fodder) in a cropping sequence was found advantageous to utilize soil nutrients more efficiently and to sustain soil fertility and productivity under intensive cropping.