Split Application and Levels of K on the Yield of Maize and Different Fractions of K in Soil.
Santhy P. Bala Sr., Tamil Nadu Agricultural Univ, Directorate of Open and Distance Learning, Coimbatore, India
Maize is globally the top ranking cereal in potential grain productivity. Among cereals grown in India, it ranks fifth in area (6.42 mha), fourth in production (11.47 mt) and third in productivity with a very low level of 1790 kg ha-1. Average grain yield of 6-8 t ha-1, however, has often been obtained during winter, which is markedly higher than that obtained in the summer season which is less than 2 t ha-1. The need and importance of potash application for harvesting high yields and superior quality produce is greater than ever before since a greater area is being reported to be mined of soil K. It can be put into practice by the addition of at least the recommended rates of K along with other needed nutrients to maintain soil K levels. The area under maize is increasing due to escalation in broiler feed production and for various food processing industries. Since maize consumes around 175 kg ha-1 of K and the application of K is far below the uptake, there is an urgent need for the replacement of K that is removed from the soil. Also, as such the existing recommendation of 50 kg K2O ha-1 to maize crop is also far below the uptake i.e. 175 kg ha-1. Hence there is a need to fix up the K dose to be applied for maize. Accordingly, an investigation was made to evaluate the yield response of maize and its yield attributes viz., cob length, cob girth, per cent of double cobs, cob filling percentage, 100 grain weight and different fractions of K viz., water soluble, exchangeable, non exchangeable, and total K to different levels as well as split application of K to maize crop. The effect of levels of K on nutrient uptake was also studied. The study revealed that application of 200 kg of K ha-1 in three split applications resulted in maximum grain yield. The yield parameters also improved due to the application of 200 kg of K ha-1 in three splits. Uptake of nutrients viz., N, P, and K were also maximum for the application of 200 kg of K ha-1. Different fractions of K viz., water soluble, exchangeable, non-exchangeable, and total K were studied at various stages of crop growth by sampling at regular intervals. Correlation among various forms of K was also worked out to study the relationship between different forms of K. The outcome of the study would enable the researchers to frame appropriate strategies so as to popularize the effect of application of K among the ultimate users of technology.
Key words: Maize, yield, yield attributes, nutrient uptake, Alfisol, water soluble K, exchangeable K, non- exchangeable K, and total K.