Peanut (Arachis hypogaea L.) is one of the most important crops produced worldwide. Peanut is the dominant crop in the typical upland red soil areas of China; however, phosphorus bioavailability in red soil is very low, which severely affects peanut production. To improve the phosphorus bioavailability, which substantially promotes the green development of peanut production, a peanut–green manure rotation field experiment was conducted with six treatments (milkvetch; radish; brassica rape; mustard rape; winter fallow and no-tillage), commencing in September 2017 in the red soil area of Jiangxi province, China. The results show that compared with no-tillage (NT) treatments, different green manure returning treatments had significant effects on soil pH, soil phosphorus components and available potassium content. The particulate phosphorus and soil available phosphorus contents in the green manure treatments were significantly higher than those in the winter fallow (WF) treatment. Compared with the WF treatment, the content of particulate phosphorous in brassica rape (BR), radish (R) and milkvetch (MV) treatments was significantly increased by 6.55%, 3.66% and 2.50%, respectively; the available phosphorus content in mustard rape (MR), BR, R and MV was significantly increased by 20.93%, 25.60%, 23.76% and 18.10%, respectively. In addition, the total phosphorus content of peanut shell in the MV and R treatment was significantly higher than that in the WF treatment, increasing by 33.47% and 60.66%, respectively. Compared with the WF treatment, the peanut biomass of MR, BR and R treatments increased significantly by 19.51%, 29.83% and 19.77%, respectively. The total phosphorus accumulation in all green manure treatments was higher than that in the WF treatment, and the MV treatment reached a significant level at 18.83%. Based on these results, the particulate phosphorus (PP) and available phosphorus were significantly affected by different green manure treatments; green manure amendment improves peanut phosphorus uptake. The use of green manure (especially milkvetch and brassica rape) can be recommended to improve phosphorus bioavailability and yield of peanut in red soil areas.

【Objective】The aim of this study was to investigate the effects of nitrogen application on yield formation and nutrient utilization of oilseed (Brassica napus L.) under different cropping systems.【Method】A field experiment was carried out in Huanggang, Hubei Province. An oilseed variety ‘Zhongyouza19’ was used as the material, setting with two cropping systems (rice-oil rotation, RO; soybean-oil rotation, SO) and four nitrogen rates (N0, 0; N1, 90 kg·hm-2; N2, 180 kg·hm-2; N3, 270 kg·hm-2) in this study. The yield and its components, dry matter accumulation, agronomic traits, nitrogen content and seeds quality were measured.【Result】(1) The oilseed yield of SO was significantly higher than that of RO, and the pods per plant, seeds per pod and 1000-seeds weight of oilseed in different cropping systems all tended to increase significantly by increasing the amount of nitrogen. Compared with N0, the seed yield of RO increased by 176.68%, 436.49% and 835.40% under N1, N2 and N3 treatments, respectively, while that of SO increased by 123.96%, 344.46% and 547.25%, respectively. Compared with RO, the seed yield under SO increased by 62.09%, 31.33%, 71.79% and 12.21% under N0, N1, N2 and N3 treatments, respectively. (2) The root crown diameter, plant height, first effective branch height and branch number of SO oilseed were significantly higher than those of RO at maturity stage, and the increase in each agronomic trait index was significant under different cropping systems with the increase in nitrogen application; the root biomass and above-ground biomass of SO were significantly higher than those of RO at all growth stages, but the root shoot ratio was lower than that of RO. The root shoot ratio decreased significantly after seedling stage in both cropping system with increasing nitrogen application. (3) Nitrogen content and nitrogen accumulation in the root, pod shell, stalk and seeds of SO were higher than those in RO, and the increases in nitrogen content and nitrogen accumulation in each part were significant with the increase in nitrogen application; the apparent nitrogen recovery efficiency under SO was higher than that under RO, and the apparent nitrogen recovery efficiency under RO increased with the increase in nitrogen application. (4) Compared with the RO, the soluble sugar content of pod shell under SO was lower, while the amino acid content and amino acid/soluble sugar content were higher with the same nitrogen application. The soluble sugar content decreased, but the amino acid content and amino acid/soluble sugar content increased with the increase of nitrogen application. Therefore, the oil content of oilseed under SO was lower than that under RO due to the limitation of fatty acid synthesis substrate, and the oil content of seeds decreased significantly with the increase of nitrogen application in cropping system. Oil yield was the maximum in both cropping system at 270 kg·hm-2 nitrogen application level, 1 678.60 and 1 665.33 kg·hm-2 for RO, and 1 684.03 and 1 687.10 kg·hm-2 for SO, respectively, but the difference in oil yield between 180 and 270 kg·hm-2 nitrogen application for SO was not significant.【Conclusion】In conclusion, the nitrogen rate for RO could be controlled at about 270 kg·hm-2, but the nitrogen rate for SO could be controlled at about 180 kg·hm-2 to ensure higher nitrogen use efficiency and higher oil yield.

[目的]长江流域多熟制模式下,油菜播种推迟,引起产量低、品质差.为探究施氮量对迟播油菜氮素利用和产量、品质的影响,本研究通过测定不同施氮量下迟播油菜产量构成、农艺性状、养分积累、籽粒品质,以期探明迟播油菜最佳施氮量.[方法]以甘蓝型油菜品种中油杂19为材料,在湖北应城、黄冈进行大田裂区试验,设置2个播期(常规播期S1,10月10日;迟播S2,11月10日)为主区,4个施氮量(N0:不施氮肥;N1:120 kg·hm-2;N2:240 kg·hm-2;N3:360 kg·hm-2)为副区.[结果](1)迟播(S2)显著降低油菜籽粒产量,增加氮肥施用量,不同播期油菜单株角果数、每角果粒数及千粒重均有显著上升趋势,与N0相比,在N1、N2和N3处理下,籽粒产量在常规播期下两地平均增加31.9％、68.6％和79.8％,在迟播下两地平均增长36.0％、82.3％和87.3％;(2)播期推迟,油菜根颈粗、株高、分枝起点高度和根系干重均显著下降,地上部干重增加,根冠比下降.增加氮肥施用量,不同播期油菜根颈粗、株高及分枝起点高度增加,地上及根系干重均上升,但根冠比呈现下降趋势;此外,与N0相比,在N1、N2和N3下,倒伏角度在正常播期下两地平均增加162.7％、254.7％和374.7％,在迟播下两地平均增长105.5％、208.7％和303.1％,即增施氮肥加重了倒伏的发生;(3)推迟播期,油菜根系氮含量和氮积累量均下降;籽粒氮含量上升而氮积累量下降、含油率下降;茎秆、角果壳氮含量变化不显著,但氮积累量显著上升.增加氮肥施用量,各部位氮含量和氮积累量增加,含油率下降,但产油量呈上升趋势,在240 kg·hm-2施氮量水平时,产油量在两个播期下均达最大,应城分别为1830.5和1534.5 kg·hm-2,黄冈分别为1535.1和1220.0 kg·hm-2.籽粒氮素利用率也达最高,应城分别为34.88％和31.14％,黄冈分别为27.95％和25.48％.籽粒氮素利用率与籽粒产量和产油量呈极显著正相关,与倒伏角度不相关,因此可以通过提高籽粒氮素利用率提高籽粒产量和产油量,同时不加重倒伏发生.[结论]增加氮肥施用可提高迟播油菜产量,但氮肥施用应控制在240 kg·hm-2左右,以控制倒伏进一步加剧,并获得最大产油量.

[目的]研究绿肥还田腐解过程中产生的有机酸阴离子对土壤中难溶性磷素的活化效果,以深化理解绿肥作物提高土壤养分供应能力的机理.[方法]供试6种绿肥作物为紫云英(Astragalus sinicus L.)、肥田萝卜(Raphanus sativus var.Longipinnatus)、二月兰(Orychophragmus violaceus)、双低甘蓝型油菜(Brassica napus L.)、双高甘蓝型油菜(Brassica napus L.)和芥菜型油菜(Brassica juncea).将绿肥植株切碎后,置于离心管中,加入土壤浸提液于室外背光处密闭腐解45天,采用离心法提取植株腐解液.测定腐解液中10种有机酸组分(丙二酸、苹果酸、柠檬酸、草酸、乳酸、酒石酸、乙酸、琥珀酸、马来酸和富马酸阴离子)含量.采用室内模拟方法,分别用6种绿肥腐解液溶解难溶性铝磷(Al-P,AlPO4)和铁磷(Fe-P,FePO4·2H2O),测定溶液中的无机磷含量.[结果]二月兰腐解液中10种有机酸组分总含量最高,其次为肥田萝卜、双低甘蓝型油菜和芥菜型油菜,双高甘蓝型油菜和紫云英腐解后腐解液中较低.所有绿肥作物腐解液中10种有机酸组分含量大小依次为酒石酸、丙二酸、柠檬酸、琥珀酸、乳酸、苹果酸、乙酸、草酸、马来酸和富马酸阴离子.其中酒石酸和丙二酸阴离子占上述10种主要有机酸总量的15％以上,马来酸和富马酸阴离子占比最低,不到总量的1％.不同绿肥腐解液对Al-P和Fe-P的活化能力有显著差异,肥田萝卜对两种难溶性磷素的活化能力最高,理论上1000 kg肥田萝卜绿肥可活化0.6～1.2 kg的Al-P和Fe-P,其次为紫云英和芥菜型油菜,对Al-P和Fe-P的活化量均约为0.6～1.0 kg,而二月兰的活化量最低,约为0.2～0.6 kg.对不同有机酸含量与难溶性磷活化量进行相关性分析发现,Al-P活化量与柠檬酸、苹果酸和草酸阴离子的含量呈现正相关关系,Fe-P的活化量与酒石酸的含量呈现正相关关系.[结论]与Al-P和Fe-P的活化密切相关的是有机酸中含有较高的柠檬酸、草酸、苹果酸和酒石酸.供试6种绿肥作物腐解液中的10种有机酸的总含量及各有机酸组分的占比差异很大.二月兰虽然有机酸总量高,但是柠檬酸、草酸和酒石酸比例均较低;而肥田萝卜腐解液中的酒石酸含量及其占比高于其他绿肥,且柠檬酸和琥珀酸占比较高,对Fe-P的活化能力强;芥菜型油菜和紫云英腐解液中草酸、柠檬酸和琥珀酸占比高于其他绿肥,对Al-P的活化能力强.供试6种绿肥中以肥田萝卜腐解液的活化能力最强,芥菜型油菜和紫云英腐解液的活化能力次之.

Excessive use of chemical fertilizers has led to a reduction in the quality of arable land and environmental pollution. Using green manure to replace chemical fertilizers is one of the most effective solutions. To study the effect of green manure on the requirement for nitrogen fertilizer in oilseed rape, a field experiment with maize–oilseed rape rotation was conducted. Green manure was intercropped between rows of maize and returned after the maize harvest, with no green manure intercropped as control. Different nitrogen fertilizer treatments (0, 65%, 75% and 100% N rates, respectively) were applied during the oilseed rape season. The results showed that with a 35% reduction in nitrogen application rate, the rapeseed grain yield was significantly higher with the maize intercropping with green manure returned to the field than with the maize monocropping treatment at the same nitrogen level. Under conditions of intercropping and return of green manure, compared with the full standard rate of nitrogen fertilizer treatment, a reduction in nitrogen application of 25–30% in the rape season had no significant effect on rape yield. The agronomic efficiency of nitrogen fertilizer on oilseed rape increased significantly, by 47.61–121%, with green manure incorporation. In addition, green manure incorporation significantly increased the soil organic matter content and the soil-available nitrogen content when chemical nitrogen fertilization was abandoned. Benefit analysis showed that a 25–35% reduction in chemical nitrogen fertilizer applied to oilseed rape crops could be achieved by intercropping green manure in the maize season before the sowing of rapeseed in the experimental area. In the long-term, this measure would increase nitrogen utility, reduce production costs, and have concomitant environmental benefits of improving the quality of cultivated land.