Optimizing timing of potassium application in productivity enhancement of crops

摘要

Among the major plant nutrients, potassium is the most abundant plant nutrient in soils. Indian soils vary widely?in their K status due to differences in origin of parent material and mineralogical make up and variation in readily available K?and non exchangeable K reserves and the soils are expected to behave becomes the most important aspect as for as K nutrition?of crop plant is concerned. The insignificant response upto certain range level of K application indicates the utilization of?added K towards fulfilling its unsatisfied state of K hunger. The effective response to K application sets in when level of K?satisfies the K hunger in soil. Time of fertilizer application may considerably influence crop response to fertilizer. The present practice of basal dose of K application has not significantly augmented rice yield especially in Vertisol under modern?intensive agriculture. Several studies conducted in Tamilnadu, Uttar Pradesh and Tripura indicated the beneficial effect of split?application of K The response of rice to applied K on a Vertisol at Raipur, showed application of 40 kg K2O ha-1 in two splits?as basal and at panicle initiation stage of rice significantly increased the grain yield. Potassium application 50 % at transplanting?and 50 % at panicle initiation along with N is recommended in Malanad where light textured soils and high rainfall conditions are prevalent. Thus, potassium can be applied in 1-3 split applications and depends on soil K buffering characteristics, crop?establishment method used and the local importance of K for reducing pest and diseases incidence. The experiments conducted with fertilizer K rate, time and method of application in Cauvery delta regions (Vertisols) showed that on clay soils (290.0 kg?ha-1 NH4OAc - K) with high K+ and NH4 + fixation potential, rice yields and N recovery efficiency can be increased by?applying K fertilizers one week before N topdressing. Basal skipping of K2O and application of entire quantity of K2O into?two equal splits resulted in higher growth, grain and straw yields of rice in both kharif and rabi seasons, respectively. It is?reported that basal skipping of K and applying K in two equal splits recorded the highest N and K uptake in grain and straw?yields in soils with medium K status. In soil of high K status level, application of 120:38:38 kg N, P2O5 and K2O in SRI rice?observed that basal skipping of K2O and application of the entire K2O in to three equal splits viz., at early tillering, active tillering and panicle initiation stages recorded higher grain and straw yields in both kharif and rabi seasons.