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

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(K₂O 75 kg·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(75 kg·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(K₂O),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.

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

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 K₂O·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.