渭北旱塬管理措施对冬小麦地土壤剖面物理性状的影响

Effects of agricultural measures on soil profile physical properties of winter wheat field in Weibei highland, China

【目的】研究黄土高原旱作农业区不同施肥覆盖措施对冬小麦地0—40 cm土壤剖面物理性质的影响,可为保持良好的土壤物理性状,探求适合渭北旱塬可持续的田间管理措施提供参考。【方法】基于设在渭北旱塬15年的田间定位试验,选取NP (N 150 kg/hm^2+P 75 kg/hm^2)、NPK (NP+K 30 kg/hm^2)、NPB (NP+biochar 14.0t/hm^2)、NPFFT (NP配合地膜夏闲期覆盖)、NPFGT (NP配合地膜生育期覆盖)和NPFWT (NP配合地膜全年覆盖)共6个处理。于2017年冬小麦收获期采集剖面土样,对0—10 cm、10—20 cm、20—30 cm和30—40 cm土层土壤含水量、土壤容重、饱和导水率和水稳定性团聚体等相关土壤物理性质进行测定与分析。【结果】与NP相比,NPK处理降低了收获期0—20 cm土壤容重,增加了耕层土壤总孔隙度和0—40 cm土层> 2 mm水稳定性团聚体含量,0—10 cm土层> 2 mm水稳定性团聚体含量显著提高了1.3倍(P <0.05);NPB处理,收获期耕层土壤容重降低,土壤总孔隙度增加,表层土壤饱和导水率显著降低27.9%,剖面土壤含水量和> 2 mm水稳定性团聚体含量均增加,且表层> 2 mm水稳定性团聚体含量显著提高了1.0倍;NPFFT处理收获期剖面土壤含水量降低,耕层土壤容重增加,总孔隙度降低;NPFGT处理收获期耕层土壤容重和剖面土壤含水量均增加,耕层总孔隙度降低,剖面土壤饱和导水率降低,尤其表层显著降低60.2%;NPFWT处理收获期耕层土壤容重增加,总孔隙度降低,表层土壤饱和导水率降低,但10—40 cm土壤饱和导水率平均提高57.5%,剖面土壤含水量、> 2 mm水稳定性团聚体含量、平均重量直径和几何平均直径均增加。受当地传统耕作深度的影响,不同施肥覆盖措施对土壤容重、饱和导水率和孔隙度的影响主要集中在0—20 cm土层,对20—40 cm土层影响较小。【结论】在氮磷肥配施的基础上,增施钾肥、生物炭和地膜全年覆盖均有利于改善试验农田土壤物理性质,但从经济投入和对土壤物理性状改良程度方面考虑,增施钾肥和地膜全年覆盖这两种处理是保持渭北旱塬良好土壤剖面物理性质的有效措施。

【Objectives】This study aimed to compare the effects of long-term different fertilization and mulching methods on physical properties in 0–40 cm soil layer of winter wheat field in arid farming area of Loess Plateau, to provide the guideline for maintaining good soil physical properties and seeking for suitable and sustainable development agricultural measures of the Weibei Highland.【Methods】A 15-years’ winter wheat field experiment, started in 2002 and located in Weibei Highland, was used in this study. Six treatments were setup, NP(N 150 kg/hm2 + P 75 kg/hm2), NPK(NP + K 30 kg/hm2), NPB(NP + biochar14.0 t/hm2), NPFFT(NP + film mulching during summer fallow period), NPFGT(NP + film mulching during growth period) and NPFWT(NP + whole year film mulching). After winter wheat harvested in 2017, samples were collected in0–10 cm, 10–20 cm, 20–30 cm, and 30–40 cm soil profiles, and the soil moisture, bulk density, saturated hydraulic conductivity(SHC) and water-stable aggregate contents were determined.【Results】Compared with NP treatment, NPK treatment decreased the 0–20 cm soil bulk density, increased the 0–20 cm soil total porosity and the > 2 mm size water-stable aggregate content in 0–40 cm profiles. The > 2 mm size water-stable aggregate content in 0–10 cm layer increased by 1.3 times(P < 0.05). NPB treatment decreased the soil bulk density, increased the soil total porosity, but decreased the SHC significantly by 27.9% in 0–20 cm layer. Both water content and > 2 mm size water-stable aggregate contents increased in the profile, and the > 2 mm size water-stable aggregate contents in the surface layer increased by 1.0 times significantly. NPFFT reduced the water content in the profile, but increased the soil bulk density and decreased the soil total porosity of tillage layer at harvest time. NPFGT reduced the water content of the profile, increased the soil bulk density but reduced the soil total porosity of tillage layer, meanwhile reduced the SHC of the profile, among which especially in the surface layer it was reduced by 60.2% significantly. NPFWT increased soil bulk density but decreased the total soil porosity of tillage layer, decreased the SHC in surface layer, but increased it in 10–40 cm layers by an average of 57.5%, meanwhile the water content, > 2 mm size water-stable aggregates content,MWD and GMD of profile were all increased. Affected by the local traditional tillage depth, the effects of different fertilization and mulch measures on soil bulk density, saturated hydraulic conductivity and porosity were mainly concentrated in 0–20 cm soil layer, while little effect had in the 20–40 cm soil layer.【Conclusions】Based on the combination of N and P fertilizations, the application of potash, biochar and film mulching around whole year could effectively improve soil physical properties. From the perspective of economic input and degree of improvement in soil physical properties, the addition of potash and whole year film mulching were effective measures to maintain the good physical properties of soil profile in Weibei Highland.