覆盖免耕在休闲期的节水和生育期的调温效应

对免耕覆盖、秸秆还田和常规耕作在休闲期的节水效果研究表明:在夏季休闲期,免耕覆盖比常规耕作多贮水30.62mm,比秸秆还田多23.91mm;在冬季储水灌溉期间,可将储水定额从2100m3/hm2减少到600和975m3/hm2。对春小麦生育期土壤表层,5、10、15、20和25cm处温度变化观测发现:免耕覆盖土壤温度在气温较低的8:00可以提高土壤表层温度,在气温较高的14:00可以减缓土壤温度的升高,而在19:00气温降低时可以减缓土壤温度的降低,使土壤温度一直保持在一个稳定的状态,这有利于调节农田小气候,创造作物良好的生长环境。     

免耕播种机试验与应用研究

主要论述了保护性耕作关键装备—2BM-9型免耕播种机的技术参数与工作原理,论述了其性能试验、可靠性试验及应用效果。通过性能试验与生产考核表明:该机各项指标均达到了设计要求,使用可靠性大于98%,调整使用方便性大于97%。经测试与调查统计知:该机对作物留茬地提高土壤含水率6%～9%,减少农田风蚀50%～80%,提高土壤有机质含量0.04%～0.08%,增加农民收入10%～15%。经过4年的推广应用,取得了良好的经济社会生态效益,对促进保护性耕作技术的实施有着重要的作用。     

Agroforestry systems and soil surface management of a tropical alfisol:

Field runoff plots, 70 x 10 m each, were established on a tropical Alifisol in southwestern Nigeria to monitor water runoff, soil erosion and nutrient loss in water runoff. The non-agroforestry control treatment (A) was established at two levels: plow-till and no-till systems of seedbed preparation. There were two agroforestry systems based on contour hedgerows of (B) Leucaena leucocephala and (C) Gliricidia sepium established at 4-m and 2-m spacings. Field plots were established in 1982 and hydrological measurements were made for uniform maize-cowpea rotation for 12 consecutive growing seasons from 1982 through 1987. Once established hedgerows of Leucaena at 2-m spacing were extremely effective in reducing water runoff and controlling erosion. Runoff, erosion and nutrient losses were generally more from maize grown in the first season than from cowpea grown in the second. Mean seasonal erosion from maize was 4.3, 0.10, 0.57, 0.10, 0.64 and 0.60 t/ha for plow-till, no-till, Leucaena-4m, Leucaena-2m, Gliricidia-2m treatments, respectively. Mean runoff in the first season from treatments listed in the order above was 17.0, 1.3, 4.9, 3.3, 4.3, and 2.4 percent of the rainfall received. There were high losses of Ca and K in water runoff from the plow-till treatment. In contrast to runoff and erosion, losses of bases in water runoff from agroforestry treatments were relatively high, high concentration of bases in runoff was probably due to nutrient recycling by the deep-rooted perennials.     

Long-Term Variable Rate Lime and Phosphorus Application for Piedmont No-Till Field Crops

Variable rate (VR) fertilizer application is a paradigm with potential to improve input efficiency and farm profitability. It is widely marketed by commercial applicators in the southeastern US. However, field studies comparing VR with traditional management have not demonstrated consistent, positive results. The objectives of this study were: (1) to determine the soil impact, crop response and economic potential of VR phosphorus (P) and lime application in a North Carolina Piedmont no-till field crop system using intensive soybean [Glycine max (L.) Merr.] production and (2) to economically evaluate alternatives to standard commercial grid soil sampling for directing VR P and lime. A 23-ha long-term no-till field in the SE Piedmont was divided into 0.4ha plots assigned to either VR or uniform P and lime application. Grid soil sampling and VR P and lime application were done prior to four crops over 3 years: full season soybean, wheat (Triticum aestivum L.)–double cropped soybean, and full season soybean. Soil test P, pH and crop yield response to VR P were inconsistent. Soil pH in areas with low pH initially did increase in response to VR lime, but it took two to three applications to bring all of these areas to the target pH. Once VR-liming raised initially low soil pH to levels close to target, yield of soybean, but not wheat, were up to 0.74Mgha^–1 higher than with uniform lime. Even with significantly higher soybean yields associated with VR lime, 3 years of grid sampling and VR application were not profitable compared to uniform application. The results indicated that VR lime could be profitable if the initial grid sampling data were used either for 2 consecutive years, or if it was used to restrict future grid sampling to specific areas requiring further VR lime.     

三种耕作制度下密西西比州两种加入家禽垫料的土壤上磷动态研究

An experiment arranged in a randomized complete block design with three replications was conducted on a Lexington soil (fine-silty, mixed, active, thermic, Ultic Hapludalfs) and a Loring soil (fine-silty, mixed, active, thermic, Oxyaquic Fragiudalfs) in Mississippi from September 1997 to September 2000 on 18 runoff plots under natural rainfall condition to study the phosphorus (P) dynamics in poultry litter amended soils under three management systems combining tillage and planting date treatments to identify effective management practices in southern U. S. A. The management systems in the study were:1) tillage in the fall prior to litter application followed by a delayed planting of fall forages (CT-DP); 2) tillage followed by immediate planting of the fall forage with subsequent litter application (CT-IP); and 3) no-till with planting prior to litter application (NT-IP). The results indicated that there was significant increase in soil P after 3 years of poultry litter application for both Lexington and Loring soils (P <0.05). Based on P budget analysis, the majority of P from poultry litter application (> 90%), was accumulated in both soils. In Loring soil, soluble P mass in the runoff was significantly higher from NT-IP than from CT-DP and CT-IP over the entire study period (P <0.01). For both soils, there were no significant differences in sediment P mass between management systems. For Loring soil, CT-DP and CT-IP were effective management practices to mitigate negative effects due to poultry litter application.     

Spatial variability of short-term effect of tillage on soil penetration resistance

The effect of tillage on soil properties varies within field due to spatial variability of soils. Mapping changes of soil penetration resistance (PR) would be useful to understand and assess tillage practices to alleviate soil compaction. The objectives were to model the short-term effect of tillage on PR and its spatial structure, and to delineate homogeneous zones based on soil response in a Typic Argiudoll previously managed under no-till. A grid sampling for PR and soil water content (SWC) were performed before and after chiselling. Spatial analysis was performed on the effect of tillage on PR data by 10 cm layers and homogeneous zones were delineated by k-means cluster analysis. The effect of tillage was ?0.33 MPa in 10–20 and 20–30 cm layer. No differences of PR were found at 0–10 cm. Short range (5–7 m) spatial structure on the horizontal plane was observed in all layers. Only 45% of the field showed a marked effect of tillage on PR. Mapping the effect of tillage on PR would be a useful approach for evaluating the global and local response of soil to tillage, as well as for delineating of areas within field for site-specific tillage practices.     

大垄双行玉米免耕播种技术研究

主要针对我国东北冷凉风沙区在玉米播种时,难以实现原垄免耕播种的问题,提出了大垄双行玉米错茬免耕垄作播种的作业思路,大垄双行技术是指将传统的一垄一行改为一垄双行,垄台宽度约为传统垄台的3倍,目前设计为700 mm;建立了相应的试验田.试验表明:该项技术能够在田间大量玉米根茬直立覆盖情况下,在大垄上实现两行玉米错茬播种,保持垄形,作业质量满足农艺要求.与传统播种方式相比,具有提高地温、降低作业成本、提高产量等优点,可以提高地温约1℃,降低机械作业成本350元/hm2,提高产量14.42%,是保护性耕作技术在东北冷凉风沙区推广应用的一种较理想的模式.     

两种小麦对行免耕播种机的对比实验

对2BMD-12型小麦对行免耕播种机和美国JD1590型进行了对比实验,内容包括机具适应的地表秸秆覆盖情况、施肥能力以及性能价格比等。结果表明,JD1590型小麦对行播种机不适用于我国一年两熟地区的小麦免耕播种;2BMD-12型小麦对行免耕播种机是专门针对我国一年两熟地区免耕播种小麦而设计的,有较好的防堵性能,能在直立玉米秸秆覆盖地直接进行小麦播种,作业质量良好。     

微耕机配套的玉米免耕播种机防堵开沟部件设计与试验

【目的】为解决我国西南地区土壤黏重,田块面积相对较小,现有免耕播种机作业时机具通过性差,播种质量难以保证等问题,设计一种微耕机配套的圆盘刀式玉米免耕播种机。【方法】应用圆盘刀与限深轮行走装置具备的破茬开沟、限深防滑功能,研究对比播种机平面、波纹与缺口圆盘刀作业时对破茬、牵引阻力和油耗等的影响;通过LS-DYNA对3种类型圆盘刀切割土壤过程进行仿真模拟,并实现关键参数的设计。【结果】田间试验结果表明,配置平面圆盘刀的免耕播种机土壤扰动量、油耗较波纹圆盘刀分别低4.03%和14.64%;较缺口圆盘刀分别低1.15%和7.51%;牵引阻力在0.54 m·s~(–1)时最低,为1.20 k N;使用3种类型圆盘刀的种肥深度合格率达85%以上,粒距合格指数为90.3%。【结论】本研究可为西南地区圆盘刀破茬的免耕播种机设计提供依据。