The Andhra Agric. J 66 (4): 606-609, 2019 Response of Groundnut (Arachis Hypogaea L.) to Nitrogen Levels and Plant Geometry Mandakranta Chakraborty, M Martin Luther Ch Pulla Rao and Ch Sujani Rao Department of Agronomy, Agricultural College, Bapatla, A.P. ABSTRACT A field experiment was conducted at the Agricultural College Farm, Bapatla on sandy upland soils during post- monsoon, 2018. The experiment consisted of four levels of nitrogen and four population densities laid out in randomized block design with factorial concept. The results revealed that among the four levels of nitrogen, application of 60 kg N ha -1 , recorded the highest drymatter accumulation, yield attributes (number of pods plant -1 , number of pops plant -1 ), pod and haulm yield and soil available nutrient. Crop geometry with 15 cm x 10 cm spacing resulted in higher drymatter accumulation, number of pods plant -1 and pod and haulm yield. Keywords: Groundnut, nitrogen levels, population densities, drymatter accumulation, yield attributes, pods, pops, pod yield, haulm yield, soil available, Nutrients. Groundnut (Arachis hypogaea L.) is one of the most important and unique legume cum oilseed crop grown particularly in southern and western parts of India. Groundnut is an important source of edible oil in India and world. Its importance lies in high oil (45%) and protein (26%) content and minerals like iron, calcium and phosphorus. Fertilizer management is a key factor in improving groundnut production with the recent changes in global agricultural commodity market. Yield is a function of plant density and hence, planting density is highly associated with yield potential and optimum density per unit area is an important non- monetary input to decide the maximum productivity of the crop. Optimum plant population and nutrient dose are necessary factors recognized to derive yield potential of a cultivar. Ammonium-sulphate applied as a source of ‘N’ is readily soluble in water and has a strong acidifying action on the soil. Ammonium ion is absorbed by negatively charged colloids in the soil and its mobility through leaching is hence reduced. As a result, the availability of nutrients like phosphorus, sulphur, zinc and iron increases which can easily be taken by the plants thus resulting in the higher pod yield. Sulphur in the fertilization also play an important role in synthesis of proteins, oils and essential amino acids. MATERIAL AND METHODS A field experiment was conducted at the Agricultural College Farm, Bapatla on sandy upland soils during post-monsoon, 2018 on response of groundnut (Arachis hypogaea L.) to nitrogen levels and plant geometry. The experiment was laid out in a randomized block design with factorial concept in three replications. The treatments consisted of four levels of nitrogen (ammonium sulphate as source) viz., 0 , 30 , 60 and 90 kg ha -1 and four levels of population densities viz., 30 x 10 cm , 25 x 10 cm, 20 x 10 cm and 15 x 10 cm. Nitrogen at 60 kg ha -1 and 90 kg ha -1 were applied in three splits i.e., 1/3 rd as basal, 1/3 rd at 30 DAS and 1/3 rd at 60 DAS. Phosphorous and potassium were applied at the rate of 40 kg ha -1 and 50 kg ha -1 respectively as basal dose to all the treatments uniformly. Gypsum was applied at early flowering stage @ 500 kg ha -1 . The soil was sandy in texture, near neutral in reaction, low in organic carbon (0.15 %), and in available nitrogen (120 kg ha -1 ) and medium in available phosphorus (29.2 kg ha -1 ) and potassium (168 kg ha -1 ). The rainfall during the crop growth period was 191.2 mm. The data on drymatter production, yield attributes, yield and soil available nutrients were recorded and subjected to statistical analysis. RESULTS AND DISCUSSION Drymatter accumulation (kg ha -1 ) Increase in nitrogen levels from 0 kg N ha -1 to 90 kg N ha -1 resulted in higher drymatter production (Table 1). Application of 90 kg N ha -1 resulted in significantly higher drymatter accumulation of 10166 kg ha -1 but was on par with 60 kg N ha -1 and superior to 30 kg N ha -1 and 0 kg N ha -1 . It was probably because of the enhanced crop growth with higher levels of nutrients, which enhanced photosynthesis and hence