烟杆还田对水稻产量和养分吸收的影响及其替代钾肥的效果

Effect of tobacco straw incorporation on rice yield and nutrient absorption and its substitute for potassium fertilizer

选择不同供钾能力的烟-稻轮作区稻田,研究了烟杆还田对水稻产量、钾素吸收利用的影响及其替代钾肥的效果.结果表明:烟杆还田(2250 kg·hm^(-2))和施钾肥(K_2O 75kg·hm^(-2))均能增加水稻产量和地上部钾素的累积量,其中烟杆还田配施钾肥的增幅最大,低钾(土壤速效钾含量<100 mg·kg^(-1))、中钾(土壤速效钾含量100~150 mg·kg^(-1))和高钾(土壤速效钾含量>150 mg·kg^(-1))土壤的水稻分别增产13.3%、17.1%和13.5%.烟杆还田(St+NP)可以提高钾素吸收利用率和农学效率.但在水稻当前推荐施肥量(75kg·hm^(-2))条件下,烟杆还田配施钾肥(St+NPK)对钾肥(素)吸收利用率和农学效率无显著影响,说明当前推荐施钾量可能偏高.通过对烟杆还田替代钾肥的计算,发现还田烟杆可以替代10%~22%的化肥钾(K_2O),烟后晚稻在烟杆还田时钾肥施用可以减少7.2~16.5 kg·hm^(-2).因此在烟杆还田条件下,高钾田块可减少化学钾肥的施用,而中钾和低钾田块为稳定水稻产量和维持土壤钾素平衡,则应保证目前推荐钾肥量的投入.

Field trails were carried to study the effects of tobacco straw incorporation and potassium （K） fertilizer on rice yield, K uptake and use efficiency, and its substitute for K fertilizer under different paddy soil K levels in tobaccorice rotation areas. Results showed that both tobacco straw incorporation （2250 kg·hm^-2） and K fertilizer application （75 kg K2O ·hm^-2） could increase grain yield and aboveground K uptake of rice. The treatment of tobacco straw incorporation with K fertilizer （St＋NPK） got the best effect on rice yield compared with the control （NP）. In this treatment （St＋NPK）, rice yields were increased by 13.3%, 17.1% and 13.5% for lowK soil （available potassium content 〈 100 mg·kg^-1）, middleK soil （available potassium content 100-150 mg·kg^-1） and highK soil （available potassium content 〉 150 mg·kg^-1）, respectively, compared with NP. Tobacco straw incorporation （St＋NP） could increase K fertilizer recovery efficiency and K fertilizer agronomic efficiency. Under the current practice of applying 75 kg K2O·hm^-2, St＋NPK showed no significant effect on K fertilizer recovery efficiency and K fertilizer agronomic efficiency, demonstrating that the recommended rate of K fertilizer might be more than the actual demand of rice growth. More importantly, data of tobacco straw substitute for K fertilizer showed that tobacco straw incorporation could replace 10%-22% K fertilizer during rice growing season, i.e. K fertilizer could be reduced by 7.2-16.5 kg·hm^-2 for rice under the condition of tobacco straw incorporation. Therefore, it was suggested that straw incorporation could reduce the rate of K fertilizer for highK soil, but the current K fertilizer inputs （75 kg K2O·hm^-2） should be supplied to get high rice yield and maintain the soil potassium balance for lowK soil and middleK soil.