NITROGEN MANAGEMENT OF SUMMER MAIZE (Zea mays L.) AS INFLUENCED BY RABI LEGUMES
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Date
2014
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
Abstract
A field experiment entitled “Nitrogen management of summer maize as influenced by rabi legumes” was conducted for two consecutive years (2011-12 and 2012-13) on sandy clay loam soils of Agricultural College Farm, Bapatla with an objective to find out the influence of rabi legume and N management on performance of summer maize. The experiment was conducted in split plot design and the treatments were replicated thrice with four legumes viz., groundnut (M1) , soybean (M2 ), greengram (M3) and clusterbean (M4) as main plot treatments taken up in rabi and four levels of nitrogen (N1:150; N2:200; N3:250 and N4: 300 kg ha-1) as sub plot treatments with maize in summer. The trial was repeated on a separate field with same type of soil in the second year. During the two years of study, in rabi season popular legume varieties viz., groundnut (TAG-24), soybean (JS-335), greengram (LGG-460) and clusterbean ( local-Sarada) were followed by the most popular and high yielding hybrid maize suitable for this region (Pioneer 30 V 92) in summer.
In the two years during rabi, the maximum gross returns, net returns and BC ratio were obtained with greengram. The total microbial population viz., bacteria, Rhizobium, Azotobacter and fungi were more after greengram and soybean crops.
The growth parameters of summer maize viz., plant height and drymatter accumulation were influenced by rabi legumes and N levels applied to maize. Greengram as preceding legume resulted in the maximum plant height and drymatter accumulation of maize at maturity during both the years. Irrespective of the year of study, plant height and drymatter accumulation were the maximum with 300 kg N ha-1 and was comparable with that of 250 kg N ha-1. Chlorophyll content (SPAD) at pre-flowering stage was more with 300 kg N ha-1 and
comparable with that of 250 kg N ha-1 during both the years of study while, at flowering (50 per cent silking) chlorophyll content was significantly higher with 300 kg N ha-1 over other levels in both the years.
Similarly, yield attributes like cobs plant-1 were significantly more with 300 kg N ha-1 and comparable with that of 250 kg N ha-1 in 2011-12 while cob length was more with 300 kg N ha-1 and comparable with that of 250 kg N ha-1 in both the years. Number of kernel rows cob-1 was more when preceded by greengram and comparable with soybean as preceding crop in 2012-13. The number of kernel rows cob-1 and kernels row-1 were significantly higher with 300 kg N ha-1 over other levels in 2012-13. Kernel weight cob-1 and 100-kernel weight of maize were more with greengram as preceding crop and with nitrogen at 300 kg N ha-1 in both the years. Similarly, more kernel and stover yields, economic returns and nutrient uptake of maize were recorded with greengram as preceding legume followed by soybean as preceding crop. The highest kernel yield of 6731 and 5803 kg ha-1 was recorded with greengram as preceding crop during first and second years, respectively, however, it was comparable with that of soybean as preceding crop (6548 and 5724 kg ha-1, respectively).The highest kernel yield of (7125 and 6405 kg ha-1) was observed with 300 kg N ha-1 in both the years which was significantly superior to other levels tested. The total uptake of N, P and K by maize at harvest was the highest with greengram as preceding crop, which was on par with soybean as preceding crop in both the years and uptake was more with 300 kg N ha-1. The soil available N, P, and K after legumes was more after soybean followed by greengram. The soil available N, P and K contents after the harvest of maize were more after groundnut and clusterbean crops.
From the experiments conducted for two consecutive years, with rabi legumes followed by maize in sequence at different nitrogen levels, it was clearly indicated that greengram-maize sequence is profitable with 300 kg N ha-1 to maize in increasing the productivity and profitability of legume-cereal sequence in Krishna agro-climatic zone of Andhra Pradesh.
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