Nitrogen use in double cropping soybean with non-fertilized winter oilseed crops

Sustainable intensification of cropping systems is a strategy to increase productivity and reduce disservices of conventional agroecosystems.Camelina[Camelina sativa(L.)Crantz]and field pennycress(Thlaspi arvense L.)are winter annual oilseed crops well suited to fill the fallow period between corn(Zea mays L.)and soybean[Glycine max(L.)Merr.]in the U.S.northern Corn Belt,but their inclusion may be limited by resource use limitations.A 2-year study was conducted from 2015 to 2017 in the U.S.upper Midwest to evaluate the effect of double cropping on winter oilseed crops and soybean productivity and economic performance.Treatments included relay-and sequential-cropped soybean with winter camelina and field pennycress,and monocrop soybean as control.Biomass and grain yield of winter oilseed crops were not affected by cropping system.Averaged over years and cropping systems,winter camelina resulted in more biomass,nitrogen(N)uptake and grain yield by 240,186 and 139% respectively,compared to field pennycress.Soybean biomass,N uptake and yield were higher in relay relative to sequential cropping.Relay soybean resulted in similar total grain yield(soybean+winter oilseed crop)compared to monocropped soybean.Double cropping soybean could maintain net return compared to monocropped soybean.Results indicate that double cropping winter oilseed crops with soybean can be economically viable in the U.S.upper Midwest.Yet,research aimed at optimizing yield through N and water use while improving ecosystem services is needed.

施氮量和灌溉定额对引黄灌区麦后复种油菜产量和水氮利用的影响

为探讨小麦后复种油菜对小麦茬残留氮素吸收利用及水氮利用的影响,以期为麦后土壤残留氮素有效利用和农业面源污染阻控提供理论依据,通过田间定位试验,研究了小麦茬施氮量[常规施氮(270 kg∙hm^(−2))、减施氮肥(202.5 kg∙hm^(−2))和不施氮(0 kg∙hm^(−2))]和灌溉定额[常规灌溉(400 mm)、节水20%(320 mm)和节水40%(240 mm)]对复种油菜的产量、氮素吸收量以及0~100 cm土壤含水率和矿质氮动态变化的影响,并进行了两季作物的氮素平衡分析。结果表明,小麦茬残留氮素对油菜产量和氮素吸收量有显著影响,氮肥后效与小麦茬的施氮量呈正比。小麦茬常规施氮270 kg∙hm^(−2)时油菜产量和氮素吸收量最高,分别为6640 kg∙hm^(−2)和25.7 kg∙hm^(−2),较小麦茬减施氮肥与不施氮分别增加11.8%与43.5%和14.8%与58.8%;小麦茬灌溉定额对油菜产量无显著影响,但对氮素吸收量有显著影响,常规施氮处理下常规灌溉处理油菜氮素吸收量较节水处理增加9.6%~10.2%。与油菜播前相比,油菜收获后施氮处理0~100 cm土层土壤矿质氮降低18.8~96.1 kg·hm^(−2);常规施氮处理较减氮和不施氮处理增加了油菜对残留氮素吸收能力。油菜翻压还田并经过冬季的冻融后,在下一季小麦播前,0~100 cm土层的土壤矿质氮增加86.1~171.8 kg·hm^(−2),增加量与小麦茬的施氮量呈正相关。常规施氮+常规灌溉定额0~100 cm土壤贮水量变化较小,氮肥后效显著提高了油菜灌溉水利用效率和水分利用效率及降水生产效率,常规施氮+节水20%处理灌溉水利用效率和降水生产效率最高,而常规施氮+节水40%处理油菜水分利用效率最高。在本试验条件下,减氮+节水20%处理的氮肥累积利用率最高,达89.8%。小麦茬施氮量为270 kg·hm^(−2),灌溉定额为320~400 mm显著提高了复种油菜的产量、吸氮量、水分利用效率和灌溉水利用效率及降水生产效率,并降低了施氮处理土壤矿质氮含量。而油菜翻压还田经过冬季冻融后显著增加了土壤矿质氮含量。

鄂东地区稻田二熟制模式的生产力、温光资源利用和氮磷养分平衡比较

为了优化鄂东地区稻田耕作制度,挖掘作物周年生产潜力,提高作物生产效益和资源利用效率,通过连续4 a的定位试验,比较了油菜-玉米(oilseed rape-maize,O-M)、油菜-水稻(oilseed rape-rice,O-R)、油菜-节水抗旱稻(oilseed rape-water-saving and drought-resistant rice,O-WDR)、小麦-玉米(wheat-maize,W-M)、小麦-水稻(wheat-rice,W-R)、冬闲-双季稻(fallow-double season rice,F-DR)6种二熟制种植模式的周年生产力、生产效益、温光资源和氮磷利用以及土壤氮磷含量变化的差异。结果显示:周年经济产量以W-R模式最高,其次为O-R模式,而平均周年生产效益以O-R模式最高;氮利用率以O-R和W-R模式在鄂最高,磷利用率以O-R模式最高,温光资源利用效率则以F-DR模式最高。经过4轮复种后,O-R模式在鄂东地区具较高的丰产性和稳产性及良好的生产效益,并有利于维持农田土壤肥力和降低氮流失风险,具有替代传统双季稻模式的应用前景。

稻油复种免耕条件下杂交油菜养分吸收、分配及转移特性研究

以杂交油菜贵杂5号为材料,研究了稻油复种免耕条件下杂交油菜养分吸收、分配及转移特性。结果表明:在现蕾期,油菜免耕移栽N、P、K吸收量比油菜翻耕移栽分别高31.2%、2.4%、60.1%,而在初花期和终花期油菜免耕移栽略低于油菜翻耕移栽,但均未达到5%的显著差异水平。在苗期免耕移栽油菜的N、P、K积累量比翻耕移栽油菜分别高14.9%、27.5%、26.8%,在角果成熟期,免耕移栽油菜N、P积累量分别比翻耕移栽油菜高3.8%、53.1%。油菜茎枝中的N、P、K积累量、转移率为油菜免耕移栽比油菜翻耕移栽低,但未达5%的显著差异水平。油菜对N、P、K吸收利用率表现为油菜免耕移栽比油菜翻耕移栽低,亦未达到5%的差异显著水平。