Biofertilizers for enhancing groundnut productivity

Abstract

Groundnut is cultivated in around 6 million ha with an annual production of around 7 million tonnes in India. However, the productivity remains a matter of great concern as it remains around 1250 kg/ha in rainfed situations and around 1800 kg/ha in irrigated conditions.As 90% of the crop is grown under rainfed conditions, productivity is affected by erratic and uneven distribution of rainfall, and in odd years the crop is badly affected by drought in most part of the country. In India groundnut is mostly cultivated in marginal lands , with suboptimal nutrient supply. Being a legume crop most of its N requirement should be met from biological nitrogen fixation. With an average pod yield of 2 t/ha, there is requirement of about 250 kg nitrogen. However, in rainfed and irrigated conditions, it is recommended to apply only 12.5 kg and 25 kg N/ha, respectively, and thus there is a requirement of about 200 kg of N being fixed by biological nitrogen fixation. However, groundnut is a promiscuous crop and is often nodulated by all the strains of rhizobia present in the tropics and sub-tropics. The situation is compounded further as native rhizobia often out-compete the inoculants strains. Thus, there is highly erratic biological nitrogen fixation in groundnut. Because of this, there is acute imbalance in the nitrogen availability in groundnut, thus affecting the productivity.