广西赤红壤区玉米氮肥效应及适宜施氮量研究

Effect of Nitrogen Fertilizer and Optimal Nitrogen Application Rate of Maize in Lateritic Red Soil Region of Guangxi

【目的】确定广西赤红壤区玉米种植体系的农田适宜氮肥施用量,为该地区玉米产业的高产高效发展及农业生态环境的保护提供理论参考。【方法】通过春-秋连续2季播种种植玉米进行田间试验,研究不同施氮量(0、180、240、300、360和480 kg/hm^2)对玉米产量、氮肥利用率、0～100 cm土层土壤无机氮残留及氮素平衡的影响。【结果】①随着氮肥用量的增加,春、秋玉米产量均呈现先增加后降低的趋势,而氮肥当季利用率则呈现显著降低趋势。②施用氮肥增加了土壤硝态氮和铵态氮残留,以硝态氮为主,且硝态氮主要残留在0～40 cm土层,铵态氮主要分布在0～20 cm土层。③施用氮肥可显著影响0～100 cm土层土壤的无机氮积累量,施氮量高于360 kg/hm^2时,土壤的无机氮积累量增加显著。土壤氮素盈余量随施氮量增加而显著增加,春玉米生长季氮肥盈余部分绝大多数在土壤中残留,到秋玉米季继续施用高量氮肥,则同时显著增加土壤氮素残留和表观损失,且氮素表观损失量增幅更大。④土壤无机氮残留量与施氮量呈显著的指数增加关系,氮肥当季利用率与施氮量呈幂函数降低关系,春玉米生长季产量、土壤无机氮残留量分别与氮肥利用率交于200和322 kg/hm^2处,秋玉米生长季产量、土壤无机氮残留量分别与氮肥利用率交于211和300 kg/hm^2处。【结论】综合考虑本试验条件下玉米春秋连作体系中的氮肥残留后效作用,兼顾作物产量、环境效应与肥料效应,广西赤红壤玉米种植区的适宜氮肥季用量为N 200～300 kg/hm^2。

【Objective】The present paper was conducted to determine the optimal nitrogen(N) application rate of maize in lateritic red soil region of Guangxi in order to provide theoretical reference for the development of high yield and high efficiency of maize industry and the protection of agricultural ecological environment.【Method】 Field experiments were carried out by sowing and planting maize for two consecutive seasons from spring to autumn to study the effects of different N application rates(0, 180, 240, 300, 360 and 480 kg/hm^2) on maize yield, N fertilizer utilization rate, inorganic N residue and N balance in soil layer of 0-100 cm.【Result】(i) Both spring maize and autumn maize yield increased and then decreased as N application rate increased.In contrast, N use efficiency decreased significantly as N application rate increased.(ii) The residual contents of NO-3-N and NH+4-N in soils were enhanced by N application. The residual Nmin was mainly NO-3-N. The residual NO-3-N was mainly distributed in 0-40 cm soil layer and the residual NH+4-N in 0-20 cm soil layer.(iii) The N treatments could increase the Nmin accumulation in 0-100 cm soil layer, especially for the N application rate of 360 kg/hm^2, the Nmin accumulation significantly increased. The soil N surplus were significantly increased with the increase of N application rates. The soil N surplus were mainly residual Nmin at spring maize season, and continued high N application rate at autumn maize season significantly increased the residual Nmin and N apparent loss, and the increasingrange of N apparent loss was even higher.(iv) There was a significant exponential increase relationship between residual contents of Nmin and N application, while the N use efficiency was reduced by power function with increasing N application rate. The maize yield and soil residual Nmin intersected with the N fertilizer utilization rate at 200 and 322 kg/hm^2 respectively in spring maize season, and at 211 and 300 kg/hm^2 in autumn maize season, respectively.【Conclusion】Under the experimental conditions, with the consideration of maize yield, the environment and N fertilization effects, the optimal nitrogen application rate should be controlled at about N 200-300 kg/hm^2 for maize.