化肥减量和有机替代对重度盐渍土水盐特性及向日葵水氮利用效率的影响

程煜; 乔若楠; 丁运韬; 董勤各; 冯浩; 张体彬

doi:10.11674/zwyf.2021173

化肥减量和有机替代对重度盐渍土水盐特性及向日葵水氮利用效率的影响

Effects of chemical fertilizer reduction and organic substitution on water and salt characteristics of high salinity soil and water and nitrogen use efficiency of sunflower

摘要

摘要:
目的研究有机肥氮替代化肥氮对盐渍化农田土壤水盐特性及作物生长的影响，为河套灌区盐渍化农田作物生产的高质量发展提供理论依据和技术支撑。
方法本研究针对河套灌区重度盐渍土于2019—2020年开展连续2年的田间试验。在同一施氮量(N 180 kg/hm²)下，设置不施有机肥(OF0)及有机肥氮分别替代化肥氮施用量的50% (OF1)和100% (OF2)处理，以不施肥为对照(CK)。测定不同时期土壤容重、质量含水率及饱和浸提液电导率(ECe)，同时在向日葵收获后测定籽粒产量及产量性状。
结果有机替代可以降低土壤容重和提高土壤孔隙度，经过两年的田间试验后，OF1和OF2处理0—40 cm土层土壤容重分别为1.46和1.43 g/cm³，较2019年播种前分别降低了3.97%和5.92%，土壤孔隙度较2019年播种前分别提高了4.94%和7.90% (P< 0.05)。有机替代显著改善盐渍土水盐特性，OF1和OF2处理显著提高了土壤含水率，OF1处理土壤含水率分别较OF0、OF2和CK提高了5.34%、3.65%和10.55% (P< 0.05)。两季向日葵生育末期OF2处理0—100 cm土层土壤ECe均值为6.77 dS/m，分别较OF0、OF1处理降低了44.10%、11.61% (P < 0.05)。有机替代提高了向日葵籽粒产量及水分利用效率，OF1处理较OF0、OF2和CK分别增产9.47%、7.52%和62.90% (P < 0.05)，分别提高净收益7.02%、23.12%和65.00% (P < 0.05)；OF1处理水分利用效率较OF0、OF2和CK分别提高了17.50%、9.52%和73.82% (P < 0.05)。此外，OF1处理较OF0与OF2处理显著提高了氮素偏生产力和氮素农学效率(P < 0.05)。
结论有机肥替代化肥能够改良河套灌区重度盐渍土土壤结构，改善作物根区土壤水盐环境，提高产量及水氮利用效率。但是有机肥全部替代化学氮肥降低了向日葵的生产效益，也没有显著提高向日葵的水肥利用效率。在当前推荐的氮磷钾肥基础上(N 180 kg/hm²)，有机肥氮替代50%化肥氮在河套灌区重度盐渍土上是可行的施肥措施。

Abstract:
Objectives The effects of different organic fertilizer ratios in total nutrient input on improving soil fertility and crop growth in heavily salinized farmland were studied for efficient and sustainable agricultural production in Hetao Irrigation District.
Methods A two-year field experiment was conducted from 2019 to 2020 in high salinity soil in Hetao Irrigation District, taking sunflower as test crop. On the basis of recommended total N input (180 kg/hm²) for sunflower, organic fertilizer was used to replace chemical N by ratio of 0 (OF0), 50% (OF1) and 100% (OF2) respectively, while no fertilizer was taken as control (CK). The soil bulk density, moisture content and electrical conductivity of saturated extract (ECe) were measured before the experiment and during the main growth stages of sunflower in 2019 and 2020. The seed yields and yield traits of sunflower were measured at harvest.
Results Application of organic fertilizers reduced soil bulk density and increased soil porosity significantly. After harvest in 2020, the soil bulk density of 0−40 cm depth treated with OF1 and OF2 was 1.46 and 1.43 g/cm³, respectively, which were 3.97% and 5.92% lower than that before sowing in 2019. The soil porosity was 4.94% and 7.90% higher than that before sowing in 2019 (P < 0.05). Organic fertilizer significantly increased the water storage and decreased ECe values of saline soil. The soil water content in OF1 was 5.34%, 3.65%, and 10.55% higher than in OF0, OF2 and CK, respectively (P < 0.05). The mean ECe of 0−100 cm depth at harvest of the two growing seasons in OF2 was 6.77 dS/m, which was 44.10% and 11.61% lower than those in OF0 and OF1, respectively (P < 0.05). The seed yield under OF1 was 9.47%, 7.52%, and 62.90% higher than that in OF0, OF2 and CK, respectively (P < 0.05). The net income was 7.02%, 23.11%, and 65.00% higher than that in OF0, OF2 and CK, respectively (P < 0.05). The water use efficiency was 17.50%, 9.52%, and 73.82% higher than that in OF0, OF2 and CK, respectively (P < 0.05). In addition, OF1 significantly increased the partial factor productivity and agronomic efficiency of applied nitrogen compared with OF0 and OF2 (P < 0.05). OF2 and OF0 had similar yield and water use efficiency, but OF2 had lower fertilizer efficiency and net income compared with OF0.
Conclusions Organic fertilizer could improve soil structure and decrease salt content of high salinity soil, ameliorate soil water and salt environment in root zone. However, organic fertilizer could substitute about 50%, not 100% of chemical fertilizers for high sunflower yield, water and nitrogen use efficiency and economic benefit of high salinity soils in Hetao Irrigation District.

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