Direct and residual effect of organic an inorganic sources of nutrients on maize (Zea mays)- mustard (Brassica napus) cropping sequence under rainfed conditions

Abstract

Maize (Zea mays L.)–mustard (Brassica campestris var. Black toria) cropping sequence is the most predominant one in sub-tropical hill ecosystems of north-eastern region (NER) of India. Mustard has been a potential crop in winter (rabi) season due to its wider adaptability and suitability to exploit residual moisture. The productivity of this system in NER is lower than the national average due to improper and imbalance nutrient use. Both the crops are nutrient-exhaustive and deplete soil fertility extensively. Poor recycling of organic sources also leads to emergence of multiple nutrient deficiencies (Kumar 2008). Hence, judicious nutrient management planning in a system perspective is the need of the hour. Keeping this in mind, present study was conducted to find out the effect of integrated application of inorganic fertilizer, Azolla compost and farmyard manure on the productivity of maize – mustard cropping system, soil fertility and economics in the mid-altitude sub-tropical Meghalaya. Field experiment was conducted at upland farm, ICAR Research Complex for NEH Region, Umiam, Meghalaya under rainfed condition during 2004–06. The institute farm is located at 25°30’N latitude, 91°51’E longitude and 950 m altitude. The soil was sandy loam in texture having 1.19 g/ cm3 bulk density, 2.67 g/cm3 particle density, 51% total porosity, 49.7% maximum water-holding capacity, low in available N (184.6 kg/ha), P (9.38 kg/ha) and medium in available K (241.5 kg/ha) with acidic reaction (pH 5.1) and high organic carbon content (1.24%). The annual average rainfall received were 1 508 mm and 614 mm during the maize- and mustard-growing season, respectively. Experiment in maize was conducted in randomized block design with 7 treatment combinations, viz T1 (Control), T2 (100% NPK 60: 60: 20 kg/ha), T3 (100% NPK + Azolla)