深翻、有机无机肥配施对稻田水分渗漏和氮素淋溶的影响

Effects of Deep Plowing and Organic-Inorganic Fertilization on Soil Water and Nitrogen Leaching in Rice Field

【目的】针对我国长江中下游地区稻麦轮作区常年浅耕与不合理施肥导致的土壤犁底层增厚与土壤板结的问题,研究深耕(打破部分犁底层)与施肥方式对稻田土壤容重、土壤紧实度、土壤水分渗漏量、氮素淋溶量及氮素形态的影响,阐明稻田氮素淋溶量与耕作、施肥方式的响应机制,为稻田合理耕层构建提供理论依据。【方法】(1)基于2015年安徽省舒城县设置两种耕作方式(旋耕12 cm、深翻20 cm)、3种等氮量施肥方式(仅施化肥处理T1、秸秆还田配施化肥处理T2、有机与无机肥配施处理T3)的田间定位试验,2019—2020年监测土壤容重与紧实度以及稻季水分渗漏与氮素淋溶量。(2)通过原状土柱模拟试验,研究深翻30 cm(打破犁底层)对稻田水分渗漏量的影响。【结果】(1)田间试验结果表明,深翻20 cm较旋耕12 cm降低了耕层土壤容重与紧实度,但没有显著增加水稻生育期的水分渗漏量,仅在分蘖期增加7.4%,孕穗期之后无显著影响。(2)土柱试验结果显示,深翻30 cm(打破犁底层)水分渗漏量较旋耕12 cm和深翻20 cm显著增加,淹水时分别增加19.0%与11.0%,非淹水时分别增加23.0%与21.5%。(3)田间试验水分渗漏液中的氮素主要以硝态氮的形式存在,T3较T1和T2处理在水稻进入孕穗期后显著降低渗漏液中硝态氮的浓度;各施肥处理间铵态氮浓度差异不显著。(4)从整个水稻生育期看,两种耕作方式对氮素淋溶量影响不显著,而3种施肥方式下氮素淋溶量存在明显差异,T3处理降低了氮素淋溶量。深翻条件下T1、T2与T3处理氮素淋溶量分别为10.69、11.74和9.14 kg N·hm^(-2),旋耕条件下分别为9.83、11.21和8.58 kg N·hm^(-2)。【结论】深翻20 cm可以改善土壤物理性状,但不会增加土壤水分渗漏及氮素淋溶;相同耕作方式下,有机与无机肥配施不会增加土壤水分渗漏与氮素淋溶。因此,在长江中下游黏质且犁底层厚(如红黄壤型)的水稻土区,部分打破犁底层,有机与无机肥配施,可构建深厚肥沃的耕作层,且不会增加水分渗漏和氮素的淋溶。

【Objective】Aimed at the problems of shallow soil plow layer,thickening of plow pan and soil hardening caused by perennial shallow ploughing and unreasonable fertilization in rice-wheat rotation area in the middle and lower reaches of Yangtze River in China,the effects of deep plowing(breaking part of plow pan)and fertilization on paddy field soil bulk density,soil compaction,soil water leaching and nitrogen leaching were studied to illuminate the response of nitrogen leaching to two tillage methods and three fertilization measures,and then provide theoretical basis for the construction of plow layer in the paddy soil.【Method】(1)Two tillage methods(rotary tillage 12 cm and deep plowing 20 cm)and three equal nitrogen fertilization treatments(single inorganic fertilizer treatment T1,returning straw with inorganic fertilizer treatment T2,organic manure with inorganic fertilizer treatment T3)were established in Shucheng County,Anhui Province in 2015.Soil water leaching and nitrogen leaching in rice season as well as soil bulk density and soil compaction were monitored dynamically in 2019-2020;(2)The soil-column experiment from paddy field was conducted to monitor.Water leaching from the treatment of deep plowing 30 cm in depth(total breaking of soil plow pan)was studied.【Result】(1)Field experiment results showed that the soil bulk density and soil compaction from the treatment of deep plowing 20 cm in depth were declined in rice season compared to those from the treatment of rotary tillage 12 cm in depth.Compared with the treatment of rotary tillage 12 cm in depth,the soil water leaching from the treatment of deep plowing 20 cm in depth increased by 7.4%in tillering stage,and there was no obvious change in soil water leaching after rice booting stage.From the whole rice growth period,the difference of soil water leaching between the treatment of deep plowing 20 cm in depth and the treatment of rotary tillage 12 cm in depth was not significant;(2)The results of soil-column experiment showed the soil water leaching from the treatment of deep plowing 30 cm in depth(total breaking of soil plow pan)increased significantly by 19.0%and 11.0%in flooding and 23.0%and 21.5%in non-flooding,respectively,compared with the treatment of rotary tillage 12 cm in depth and the treatment of deep plowing 20 cm in depth;(3)Nitrate nitrogen was dominant form of nitrogen in the soil water leaching.The concentration of nitrate nitrogen in soil water leaching from T3 treatment decreased significantly compared with that of T1 and T2 treatment after rice booting stage,but the difference of ammonium nitrogen concentration in soil water leaching from T1,T2 and T3 treatment were not significant;(4)From the whole growth period of rice,the difference of nitrogen leaching from the treatment of rotary tillage 12 cm in depth and the treatment of deep plowing 20 cm in depth was not significant,while the three treatments of fertilization had obvious difference on nitrogen leaching.Under the condition of deep plowing 20 cm in depth,the nitrogen leaching rates of T1,T2 and T3 treatment were 10.7,11.7 and 9.1 kg N·hm^(-2)respectively,and under the condition of rotary tillage 12 cm in depth,the nitrogen leaching rates of T1,T2 and T3 treatment were 9.83,11.21 and 8.58 kg N·hm^(-2),respectively.T3 treatment decreased significantly nitrogen leaching compared to T1 and T2 treatment.【Conclusion】Deep plowing 20 cm in depth can improve soil physical structure,however,soil water leaching and nitrogen leaching are not significantly increased,and the combination of organic manure and inorganic fertilizer can significantly reduce nitrate nitrogen leaching.These results are of theoretical significance for the building of deep and fertile tillage layer in the clay paddy soil with high plow pan(such as red-yellow soil)in the middle and lower reaches of the Yangtze River through deep plowing measures,combined application of organic manure and inorganic fertilizer.