Study On Potassium Fertilization Effect And The Nutrition Diagnosis Of Potassium Applied For Cotton In Hubei Province

In This study,92cotton field trials were carried out in Hubei province during2009-2011.The aims were to study:1) effects of potassium (K) fertilizer application on yield, profit and K use efficiency of cotton;2) the relationship between soil available potassium content and cotton relative yield, to establish abundance&deficiency indices of soil K nutrient;3) the relationship between cotton leaf potassium content and seed cotton yield, amount of K fertilizer through the potash field trials of6potassium gradient level.4) Potassium nutrition diagnostic index and recommend model in main growth stages of cotton, and provide the basis for installments fertilization on cotton. The main results were shown as following:1. The results showed that seed cotton yield increased significantly when K was supplied adequately. Compared with without K treatment, K fertilizer application increased the average seed cotton yield by495kg/hm, the average increment rate was15.5%. However, there was still15.2%of the test potassium had no effect.2. The results revealed that the average profit and the value cost ratio (VCR)of cotton were1519yuan/hm2and2.9, respectively. Based on current facts in agricultural production in China, significant profit was regarded as VCR above2.0.Among the92experiments,68.3%showed significant profit from input of K fertilizer. However, there was10.9%of the experiment economic benefit was negative, and there was the phenomenon of increasing output without increasing profit.3. The result showed that K fertilizer efficiency on cotton was low in Hubei Province, the average agronomic efficiency (AE) was3.3kg/kg K2O, and partial factor productivity (PEP) was26.6kg/kg K2O, physiological efficiency (PE) and recovery efficiency (RE) were19.1kg/kg K2O and19.5%, respectively. Compared with the whole sample, the K fertilizer efficiency of potassium efficiently sample was higher.4. It was found the soil available potassium content were significantly negative linear correlated with the K fertilizer effect, economic benefit and K fertilizer efficiency. Compared to the complete treatment, the relative yield of80%,90%and95%obtained from the without K treatment were selected to establish the abundance&deficiency indices of soil available K for cotton in Hubei Province, the abundance&deficiency indices of soil available K were>150,105～150,50～105and<50mg/kg. 5. The concentration of K applied had evident effects on cotton agronomic traits, and helped to improve the accumulation of cotton biomass, K content and K accumulation. The relationship between the amount of applied K fertilizer and seed cotton yield was by the quadratic equation. The simulated result showed that, the highest seed cotton yield to4196kg/hm2when the applied K fertilizer was232.5kg/hm2in the whole growth period.6. There were significant or highly significant correlation between the potassium content of pre-main stem leaf or petiole during the stages of early florescence, flower peak, boll peak and pre-boll opening and the seed cotton yield and the amount of K applied, so their K content of every period could be used as K nutrition diagnosis indicators. Different indicators would be chosen in different periods.7. The K content of middle leaf, upper leaf, lower leaf and the absolute value of difference between middle leaf and upper leaf would be as K nutrition diagnosis indicators during the stages of early florescence, flower peak, boll peak and pre-boll opening, the critical value of K content were3.1%,1.8%,2.5%and0.5%, respectively. Then used the model of cotton K fertilizer commendation, you can get the amount of K2O were25kg/hm2,37kg/hm2,25kg/hm2and71kg/hm2for K content every0.1%decrease at the main growth stages of cotton.