Effects of potash fertilizer on soil enzyme activity and nutrient content in hybrid millet rhizosphere

The field experiment was conducted,taking hybrid millet 'Zhangzagu 5' as the research object,to study the effects of potassium fertilization on soil enzyme activity(including urease,catalase and sucrase) and soil nutrients content in the later growth stages of hybrid millet for providing the best potassium application measures for the purpose of high yield.The results showed that in the later growth stages of hybrid millet,potassium application could increase soil catalase activity.Compared with control treatment(KO,no potassium fertilizer used),potassium application decreased the soil urease activities of hybrid millet rhizosphere by 13.65%-21.52%,8.77%-16.67%,7.74%-19.91%respectively and decreased soil invertase activities by 12.29%-18.50%,12.28%-19.34%,11.11%-22.50%respectively in heading,filling and maturity stages of hybrid millet.Compared with control treatment(K0),potassium fertilizer application decreased soil alkali-hydrolyzable nitrogen and available phosphorus contents by 7.00%-26.65%and 2.43%-7.80%respectively and the available potassium content was increased by 18.20%-66.21%with potassium use.The hybrid millet yield had a very significant and negative correlation with soil urease and surcease activities and soil alkali-hydrolyzable nitrogen content,and had a very significant and positive correlation with soil available potassium content in the hybrid millet rhizosphere.The treatment K3 with the K_2O rate of 300 kg/hm~2 and all as a base fertilizer had the highest grain yield and was the optimal plan of potassium fertilization of hybrid millet 'Zhangzagu 5' for maintaining the soil enzyme activities and soil fertility in millet rhizosphere and ensuring high yield in this region.