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911.
H. Riley M. Bakkegard 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):217-223
Abstract Changes in soil organic matter (SOM) content are presented for a 25 ha research farm, based on measurements in 1952, 1976, 1986 and 2002, and for 291 arable fields located throughout southeast Norway, which were sampled in around 1991 and again in 2001. Large declines were found in most cases at the research farm, especially for soils with high initial levels of SOM. The declines between 1952 and 1976 were thought to be partly due to increased depth of ploughing and improved drainage, while those in the latter period may in part be related to climatic change. Declines were also found since 1990 in the majority of the arable fields sampled, and the declines were proportional to the initial SOM level in this case also. No single causative factor was isolated for these declines, but the proportions of autumn tillage and of row crops in the rotation may be involved. A mean relative decline rate of around 1% per year of the initial SOM level was observed both at the research farm and in the arable fields. There was, however, also an indication that the percentage relative decline rate was proportional to one-tenth of the initial SOM. These two alternative scenarios suggest that soils with current SOM levels of 4%, 6% and 10%, will reach a possibly ‘critical’ level of 3% in 30–80, 70–165 and 120–230 years time, respectively. 相似文献
912.
D. Bilalis N. Sidiras E. Vavoulidou A. Konstantas 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(5):440-446
Abstract Earthworms influence soil fertility, and their population is known to be influenced by fertilization. The objective of this study is to characterize the abundance of earthworms under three different kinds of rotation-crops (Rotation: cereals–legumes for green manure-cotton), three tillage systems (Conventional Tillage CT, Minimum Tillage MT, & No-Tillage NT) and fertilization (NP: inorganic and FYM: farmyard manure-organic). Significantly higher populations of earthworms were found under the legumes and NT system in contrast to the lowest abundance determined under the cotton and CT system. Earthworm populations benefited more from organic fertilization than from NP. Our study showed that the most important factors for earthworm abundance are the macropores and Corg under Mediterranean conditions. No-till management considerably influenced the improvement of the physical and chemical soil properties and increased the earthworm abundance. 相似文献
913.
冬小麦-夏玉米轮作体系灌溉制度多目标优化模型 总被引:9,自引:3,他引:6
该文针对望都灌溉试验站全年作物种植模式,分别建立冬小麦及夏玉米水分生产函数模型,运用粒子群优化算法(PSO)求解模型中的敏感指数,并以该模型为基础建立冬小麦-夏玉米全周期灌溉制度多目标优化模型,利用改进分组非支配排序遗传算法(GNSGA-Ⅱ)对模型进行求解,得出全年不同可用灌溉水量情况下的灌水日期与灌水量。结果显示,随着可用总灌水量的增加,冬小麦和夏玉米的灌水量与产量均随之增加,但由于受到两种作物不同敏感指数的影响使得二者增加的趋势有所不同。当全年总灌水量为472mm时两种作物均接近充分灌溉,若继续增加灌溉水量,则灌水的边际效益逐渐减小。依据优化结果可在全年合理分配利用有限的水资源以获得较高的作物总产值。 相似文献
914.
菜-稻轮作对菜田氮、磷利用特性和富集状况的影响 总被引:5,自引:0,他引:5
菜田氮、磷污染治理的最佳途径是提高化肥利用率.本研究开展了四季豆(Phaseolus vulgaris)-瓢瓜(Lagenaria sicerariae)-早稻轮作中不同氮、磷肥用量的3年定位田间试验.结果表明,经济施肥量为四季豆N 155kg/hm2和P2O579 kg/hm2、瓢瓜N 247 kg/hm2和P2O5 130 kg,/hm2,早稻不施肥.取得最佳经济效益的施肥处理,净增收比其他氮、磷水平提高1.6%~46.8%,氮肥利用率从四季豆和瓢瓜连作的45.1%提高到四季豆-瓢瓜-早稻轮作的65.6%,磷肥利用率则从17.9%提高到26.5%.四季豆-瓢瓜-早稻轮作的土壤硝态氮和有效磷含量分别为四季豆和瓢瓜连作的27.5%和87.0%,为基础土壤硝态氮和有效磷含量的63.7%和93.9%.养分吸收特性分析表明,四季豆的氮、磷最大吸收速率分别是早稻的25.1倍和2.5倍,瓢瓜则分别是早稻的18.4倍和1.2倍;四季豆的氮、磷最大吸收量分别是早稻的1.7倍和2.2倍,瓢瓜则分别是早稻的2.5倍和1.9倍.因此,菜-稻轮作体系利用了蔬菜和水稻在氮、磷吸收强度上的差异,较蔬菜连作促进了氮、磷高效利用,从而削减菜田过高的氮、磷富集,降低了土壤氮、磷流失潜力. 相似文献
915.
猪粪沼液施用对稻、麦产量和氮磷吸收的影响 总被引:11,自引:0,他引:11
在江苏太湖稻麦轮作区,开展了连续2年不同沼液替代化肥比例及沼液基追比的等氮田间试验,结果表明:单施化肥处理(NPK)及沼液化肥配施处理水稻、小麦生物量及产量均显著高于无肥对照,各处理以75%沼液替代比例分3次施入(N75%)处理的水稻生物量和产量为最高,其生物量及产量分别比单施化肥处理提高2.7%和7.5%;而小麦生物量和产量以50%沼液替代比例(N50%)处理最高,其生物量和产量比单施化肥处理分别提高15.9%和7.8%.沼液化肥配施对稻麦的增产作用主要体现在提高水稻与小麦总穗数及穗粒数上;各处理水稻、小麦的氮素累积量和氮素当季表观利用率分别以75%(N75%)和50%(N50%)替代比例为最高;在50%~ 100%替代比例内沼液分次施用,水稻、小麦氮肥农学效率、偏生产力都高于化肥处理.水稻、小麦不同器官的氮分配比例显示,沼液配施化肥促进氮素向籽粒转移;相同沼液替代比例下,沼液分次施用水稻、小麦的产量、氮素累积量及氮素利用率均较基肥一次性施入高.稻、麦根、叶部磷含量分别以N75%和N100%处理最高.以上表明稻麦配施50% ~ 75%的沼液分3次施用,可获得与纯化肥处理相当的产量,且在一定程度上提高稻麦氮素利用率. 相似文献
916.
Chika Suzuki Norikuni Oka Kazunari Nagaoka Toshihiko Karasawa 《Soil Science and Plant Nutrition》2013,59(3):288-296
A better understanding of the relationships among different cropping systems, their effects on soil microbial ecology, and their effects on crop health and productivity is necessary for the development of more efficient, sustainable crop production systems. We used denaturing gradient gel electrophoresis (DGGE) to determine the impacts of crop rotations and crop types on bacterial and fungal communities in the soil. The communities of bacterial 16S rRNA genes and fungal 18S rRNA genes were analyzed in experimental field plots that were kept under 4 different crop rotation systems from 1999 to 2008 (continuous cabbage (Brassica oleracea var. capitata L.), cabbage–lettuce (Lactuca sativa L.) rotation, cabbage–radish (Raphanus sativus L. var. longipinnatus L.H. Bailey) rotation, and a 3-year crop rotation). A principal component analysis (PCA) and a canonical correspondence analysis (CCA) revealed that both the bacterial and fungal communities in bulk soils were influenced by the crop rotation systems. However, the primary factors influencing each community differed: bacterial communities were most affected by soil properties (especially carbon content), while fungal communities were influenced most strongly by rotation times. To elucidate factors that may cause differences in crop rhizosphere microbial communities, the microbial communities in the harvested cabbage rhizospheres were also analyzed. The results suggest that the fungal communities in bulk soil are related to the rhizosphere fungal communities. Our present study indicates that the microbial communities in bulk and rhizosphere soils could be managed by crop rotation systems. 相似文献
917.
《Soil Science and Plant Nutrition》2013,59(5):794-806
Abstract A regional evaluation of the soil organic carbon (SOC) dynamics for the chernozem zone in northern Kazakhstan is now vitally important for agricultural and environmental policy making. The objectives of the present study were: (1) to predict spatial and temporal variability in C input as crop residues using multi-temporal MODIS satellite images, (2) to clarify spatial and temporal variability in CO2 emission as SOC output using geostatistics and model s, (3) to clarify spatial and temporal variability in the SOC budget using the results from (1) and (2). The mean growing-season C input as plant residues in cereal fields ranged from 0.9 to 1.4 Mg C ha?1, with higher values in wet years. Carbon input as plant residues was higher in the northern part of the area than in the other parts. The average growing-season CO2 emission ranged from 0.9 to 1.1 Mg C ha?1, and was also higher in wet years than in dry years. In addition, more CO2 was emitted in the northern part of this area. Accordingly the average growing-season C budget ranged from –0.2 to 0.3 Mg C ha?1 and showed a negative correlation with air temperature during the crop-growing season. The 5-year C budget for different crop rotation systems ranged from –1.0 (3-year cropped cereal with 2-year bare fallow) to 0.4 (5-year continuous cereal cropped) Mg C ha?1. These results indicate that fallow-based crop rotation systems are degradative with regard to the SOC budget in the studied area. 相似文献
918.
Postlarvae (PL) of Macrobrachium rosenbergii (de Man 1879) were stocked at 1, 2, 3 and 4 PL m?2. Prawns were fed only pellets (P) and a combination of pellets and snail meat (PS) with three replications in 100 m2 plots in the rotational prawn–rice system. Water levels were 0.3–0.6 m in rice growing areas. The water temperatures at noon in the hot months were higher than the suitable range for prawns. The final mean weights of prawns in treatments 1, 2 and 3 PL m?2 were significantly higher than in treatment 4 PL m?2 (P<0.05). The yields from different density treatments ranged from 194±82 to 373±32 kg ha?1 and increased significantly with the increases in prawn densities (P<0.05). There was no significant difference between the two types of feed on production parameters (P>0.05). The total cost significantly increased at higher densities (P<0.05), but it was not different between feed types (P>0.05). Net profit and cost benefit ratio of treatment PS were significantly higher than in treatment P. In the present study, treatment 3 PL m?2 and treatment PS offered the optimal results. 相似文献
919.
920.
Ting LUO Prakash LAKSHMANAN Zhongfeng ZHOU Yuchi DENG Yan DENG Linsheng YANG Dongliang HUANG Xiupeng SONG Xihui LIU Wen-Feng CONG Jianming WU Xinping CHEN Fusuo ZHANG 《农业科学与工程前沿(英文版)》2022,9(2):272