利于小麦—玉米轮作田土壤理化性状和作物产量的耕作方式研究

Study of tillage patterns suitable for soil physicochemical properties and crop yields in wheat /maize fields

【目的】干旱缺水是陕西渭北旱塬粮食生产的主要矛盾。该区长期采用单一土壤耕作方法,造成土壤质地紧实,蓄水纳墒和提供营养的能力变差,直接影响粮食作物产量的提高。本文通过多年不同轮耕方式定位试验研究,旨在探讨免耕/深松、深松/翻耕和翻耕/免耕3种土壤轮耕模式对旱地冬小麦—春玉米轮作田土壤理化性状和作物产量的影响。【方法】以平衡施肥(每公顷基施N 150 kg、P2O5120 kg和K2O 90 kg)为主处理,免耕、深松和翻耕3种耕作方式组成免耕/深松、深松/翻耕和翻耕/免耕3种土壤轮耕模式为副处理,以连年免耕、连年深松和连年翻耕为对照,进行为期连续4年(2007~2011年)的土壤轮耕结合平衡施肥定位试验,详细探讨了不同土壤处理模式对土壤的理化性状和作物产量的影响。【结果】在四年试验中,免耕/深松、深松/翻耕和翻耕/免耕模式下的0—40cm土壤容重较连年免耕分别降低4.50%、6.45%和3.57%,深松/翻耕较连年深松无差异,而较连年翻耕降低1.78%。深松/翻耕较对照组0—40 cm土壤有机质、全氮、全磷、全钾、碱解氮和速效钾分别增加0.27%~15.60%、3.14%~8.61%、3.76%~24.32%、15.62%~25.17%、10.90%~14.43%、8.61%~15.53%,翻耕/免耕较连年翻耕仅有机质、全氮、碱解氮和速效钾含量提高。各处理的0—40 cm土壤】0.25 mm水稳性团聚体含量依次为连免】免/深】连深】深/翻】翻/免】连翻,连免显著高于(P【0.05)其他处理1.1~2.5倍。冬小麦和春玉米籽粒产量有3年表现为深松/翻耕】免耕/深松】翻耕/免耕,2009年在免耕/深松轮耕模式下春玉米产量显著高于深松/翻耕模式。其余免耕/深松较连年免耕增产12.05%(P【0.05),深松/翻耕较连年免耕增产18.15%(P【0.05)、较连年深松增产4.55%(P【0.05),较连年翻耕增产11.22%(P【0.05),比免耕/深松和翻耕/免耕分别增产5.44%(P【0.05)和14.57%(P【0.05);而翻耕/免耕则在各方面的效应下降,增产效果降低,较连年翻耕减产2.92%(P【0.05)。总之,以免耕/深松和深松/翻耕轮耕模式可创造良好的土壤耕层结构,增加水稳性团聚体,降低耕层及耕层以下土壤容重,提高土壤养分,促进作物生长发育。其中以深松/翻耕轮耕模式的效果较为明显,增产效果更突出。【结论】在渭北旱塬干旱少雨的生态环境下,深松/翻耕土壤耕作模式可以显著改善土壤的理化性状,提高土壤水性团聚体,降低土壤容重,释放土壤养分,从而提高作物产量,是陕西省渭北旱塬及类似地区冬小麦、春玉米一年一熟制作物轮作模式最佳的土壤轮耕模式,其次是免耕/深松轮耕模式。

Objectives]Weibei Highland, part of Loess Plateau of China, is characterized by drought and rainless throughout the year, and the lack of natural rainwater is the main reason for crop cultivation.A long-term practice of applying single soil tillage treatment in this area causes soil compaction, poor ability of storing rainwater and&nbsp;providing nutrition, influencing the crop yields.In this study, the effects of different rotational tillage patterns on soil physicochemical properties and crop yields were investigated by conducting a long-term experiment in wheat/maize fields.[Methods]A four-year field experiment was conducted.Balance fertilization ( N 150 kg, P2 O5 120 kg and K2 O 90 kg per hectare) was used as main plot and tillage systems including notillage/subsoiling rotation pattern ( NT/SS) , sub-soiling/ploughing rotation pattern ( SS/P) and ploughing/notillage rotation pattern ( P/NT) were used as subplots.Continuous no-tillage, sub-soiling and ploughing were used as controls.[Results] Compared with the continuous no-tillage, the soil bulk density of 0-40 cm soil layer under NT/SS, SS/P and P/NT was decreased by 4.50%, 6.45% and 3.57%, respectively.No difference was found between SS/P and continuous subsoiling.The SS/P decreased the soil bulk density by 1.78% compared with continuous ploughing.Compared with controls, organic matter content, total N, P, K contents, available N and K contents in 0-40 cm soil layer under SS/P are increased by 0.27%-15.60%, 3.14%-8.61%, 3.76%-24.32%, 15.62%-25.17%, 10.90%-14.43%, 8.61%-15.53%, respectively.The organic matter content, total N and available N content under P/NT are increased compared with continuous ploughing.The >0.25 mm water-stable aggregate contents of different tillage patterns in 0-40 cm soil depth are in order of continuous NT>NT/SS >continuous SS >SS/P>P/NT >continuous ploughing.The water-stable aggregate contents under continuous no-tillage is significantly higher than all the other treatments (1.1-2.5 times) .The four-year average yields of both winter wheat and spring maize in SS/P are higher than in NT/SS and P/NT, except the spring maize yield in 2009.Compared with continuous no-tillage, NT/SS increased crop yields by 12.05%(P<0.05).Compared with continuous no-tillage, continuous sub-soiling and continuous ploughing treatments, the crop yields under the SS/P were significantly increased by 18.15%, 4.55% and 11.22%, respectively.The crop yields in SS/P are 5.44% and 14.57%higher than those in NT/SS and P/NT.The of P/NT is weak in the investigated soil physicochemical effects and the crop yields is decreased by 2.92%(P<0.05).In general, NT/SS and SS/P systems had the better abilities of reducing soil bulk density, increasing soil water-stable aggregate, improving soil nutrients and promoting crop growth and development.[Conclusions] In drought and rainless regions, the sub-soiling/ploughing rotation pattern could significantly improve the soil physicochemical properties, increase water-stable aggregates content, decrease soil bulk density, thereby stimulate the release of soil nutrition and improve crop yields.Therefore, no-tillage/sub-soiling rotation and sub-soiling/ploughing rotation patterns can be employed in Weibei Highland and similar areas for improving soil fertility and crop yield.