临汾市实行禁牧轮牧的探索与实践

在全面推进我国水土保持生态体系建设中 ,临汾市水利水保部门探索出了一条以禁牧轮牧为主要内容的正确处理林牧矛盾、实现人与自然和谐共处、支撑经济社会可持续发展的新路子 :水土流失严重的山区县 (市 )作出了禁牧轮牧、加快生态建设的决定、规定 ,由政府组织实施 ,并把该项工作作为考核领导政绩的内容之一 ,实行奖惩兑现 ;对发展畜牧业做出科学规划 ,大力种植优良牧草 ,改革饲养方式 ,引进优良圈养品种 ,加强对农民的技术培训 ,走畜牧产品深加工之路 ;实行行政首长负责制、工作人员责任制、违法违纪监督制 ,确保禁牧轮牧工作的开展     

麦-豆和麦/玉/豆体系中大豆的磷肥增产增效作用研究

【目的】小麦/玉米/大豆旱地三熟模式是我国西南山丘区的主要旱作耕作模式,大豆作为该体系中改善土壤环境的核心作物,明确其增产、增效作用,可指导该体系的科学管理。【方法】于2012、2013年连续2年进行田间试验,采用小麦-大豆(单作)和小麦/玉米/大豆(套作)两种体系,设置5个不同磷水平处理(SP1、SP2、SP3、SP4、SP5),调查了大豆在与玉米共生期和玉米收获后的生物量变化,以及收获期籽粒产量、全株养分含量和养分利用效率的差异。【结果】1)玉米收获前大豆植株地上部生长率,单作为1.52 g/(m2·d),套作为1.18 g/(m2·d),单作比套作高28.8%;玉米收获后,大豆植株地上部生长率,单作为4.15 g/(m2·d),套作为5.60 g/(m2·d),套作显著高于单作34.9%。2)大豆籽粒产量套作平均比单作高20.3%。单作、套作大豆籽粒产量均随土壤磷含量的增加呈先增加后降低的变化趋势,2年平均产量最高均在SP4处理,套作为2923 kg/hm2,单作为2400 kg/hm2。SP4处理产量与SP2和SP3差异不显著,与SP1和SP5差异显著。3)收获期大豆籽粒氮、磷、钾含量套作高于单作,茎、荚含量套作低于单作;各部位的氮含量随土壤磷含量的增加先增高后降低,磷、钾含量有随土壤磷含量的增加而增加的趋势。4)小麦+大豆种植带的植株氮、钾积累量,套作体系明显高于轮作体系,且随土壤磷含量的增加先增加后减少。5)小麦+大豆种植带磷肥当季利用率随土壤磷含量的增加而逐渐减小,SP2、SP3、SP4、SP5处理套作体系比单作体系分别高44.6%、74.9%、66.9%、109.5%,平均高74.0%。【结论】套作大豆相比单作大豆具有产量和营养优势,套作大豆茎、荚氮、磷、钾养分相比单作大豆可更多地向籽粒转运,大幅提高其对磷肥当季利用效率。合理施用磷肥也可提高大豆产量。     

旱地轮作对西藏中部土壤恢复过程的影响

于西藏中部生态条件下,就麦类作物轮作、麦油轮作对土壤化学和生物性质的影响以及农田养分平衡等进行了初步研究。结果表明,不同轮作方式对土壤化学和生物学过程具有显著不同的影响。轮作周期内春青稞→春油菜、春小麦→春油菜轮作对以细菌为主导的土壤微生物的生长与繁殖具有显著的促进作用,耕层土壤有机质、全氮、全磷的绝对增长量分别达3.05~3.06g/kg,0.06~0.07g/kg,0.01~0.26g/kg。麦类作物间,春小麦→春青稞轮作对土壤肥力亦具明显的恢复作用;春小麦→春小麦连作、春青稞→冬小麦轮作土壤微生物区系构成不甚协调,土壤细菌数量明显较低,0~30,31~60cm土层有机质、全氮、全磷总体呈不同程度的退化趋势。在较高外源钾投入条件下,不同轮作方式的土壤钾素均呈不同程度的亏缺状态。     

Microbiological parameters as indicators of soil quality under various soil management and crop rotation systems in southern Brazil

The objective of this work was to identify soil parameters potentially useful to monitor soil quality under different soil management and crop rotation systems. Microbiological and chemical parameters were evaluated in a field experiment in the State of Paraná, southern Brazil, in response to soil management [no-tillage (NT) and conventional tillage (CT)] and crop rotation [including grain (soybean, S; maize, M; wheat, W) and legume (lupin, L.) and non-legume (oat, O) covers] systems. Three crop rotation systems were evaluated: (1) (O/M/O/S/W/S/L/M/O/S), (2) (O/S/L/M/O/S/W/S/L/M), and (3) (O/S/W/S/L/M/O/M/W/M), and soil parameters were monitored after the fifth year. Before ploughing, CO₂-emission rates were similar in NT and CT soils, but plough increased it by an average of 57%. Carbon dioxide emission was 13% higher with lupin residues than with wheat straw; decomposition rates were rapid with both soil management systems. Amounts of microbial biomass carbon and nitrogen (MB-C and MB-N, respectively) were 80 and 104% higher in NT than in CT, respectively; however, in general these parameters were not affected by crop rotation. Efficiency of the microbial community was significantly higher in NT: metabolic quotient (qCO₂) was 55% lower than in CT. Soluble C and N levels were 37 and 24% greater in NT than in CT, respectively, with no effects of crop rotation. Furthermore, ratios of soluble C and N contents to MB-C and MB-N were consistently lower in NT, indicating higher immobilization of C and N per unit of MB. The decrease in qCO₂ and the increase in MB-C under NT allowed enhancements in soil C stocks, such that in the 0–40 cm profile, a gain of 2500 kg of C ha⁻¹ was observed in relation to CT. Carbon stocks also varied with crop rotation, with net changes at 0–40 cm of 726, 1167 and −394 kg C ha⁻¹ year, in rotations 1, 2 and 3, respectively. Similar results were obtained for the N stocks, with 410 kg N ha⁻¹ gained in NT, while crop rotations 1, 2 and 3 accumulated 71, 137 and 37 kg of N ha⁻¹ year⁻¹, respectively. On average, microbial biomass corresponded to 2.4 and 1.7% of the total soil C, and 5.2 and 3.2% of the N in NT and CT systems, respectively. Soil management was the main factor affecting soil C and N levels, but enhancement also resulted from the ratios of legumes and non-legumes in the rotations. The results emphasize the importance of microorganisms as reservoirs of C and N in tropical soils. Furthermore, the parameters associated with microbiological activity were more responsive to soil management and crop rotation effects than were total stocks of C and N, demonstrating their usefulness as indicators of soil quality in the tropics.     

Rotation and tillage effects on soil organic carbon sequestration in a typic Hapludalf in Southern Ontario

Increased use of conservation tillage is being considered as a way to sequester atmospheric C in the soil. However, little information exists on the effect of rotation and its interaction with tillage on soil organic carbon (SOC). A research trial with combinations of rotations and tillage treatments was sampled 20 years after its establishment to assess the effects on SOC sequestration in a typic Hapludalf in southern Ontario, Canada. The cropping treatments included continuous corn (zea mays L.), six rotations comprised of 2 years of corn following 2 years of another crop or crop sequence, and continuous alfalfa (Medicago sativa L.). Each rotation was split into either fall moldboard plow (MP) or fall chisel plow (CP) treatments. Continuous alfalfa was plowed and replanted every 4 years. Soil samples were taken incrementally to a depth of 40 cm and SOC and bulk density determined. The average SOC concentration (0–40 cm) was greatest in continuous alfalfa (18.0 g C kg⁻¹). The treatments of soybean (Glycine max L.Merr.)+winterwheat (Triticum aestivum L.) or barley+barley (Trifolium pratense L.) (interseeded with red clover) followed by 2 years of corn had higher SOC concentrations (17.2–17.3 g C kg⁻¹) than continuous corn and the treatments of 2 years of corn following 2 years of alfalfa or soybean (16.4–16.5 g C kg⁻¹). The rotation of 2 years of barley followed by 2 years of corn had the lowest SOC concentrations (15.2 g C kg⁻¹). On an equivalent mass basis, the rotations of soybean+winterwheat or barley+barley (underseeded with red clover) followed by 2 years of corn, had 2–9 Mg ha⁻¹ more C than the other corn-based rotations. Including red clover in the winter wheat seemed to accelerate the rate of C mineralization compared to winter wheat without red clover; whereas interseeding red clover with barley increased SOC contents compared to excluding red clover in the barley rotation. More SOC was found in the top 10 cm and less in the 10–20 cm depth of the CP than in the MP soils. However, the CP did not increase the SOC content (0–20 cm) above that of MP indicating that this form of reduced tillage did not increase C sequestration in any of the rotations on this soil.     

施肥培肥措施对春玉米农田土壤氨挥发的影响

采用通气法进行不同秸秆还田方式、施肥时期和方法对春玉米农田土壤氨挥发影响的研究。结果表明,秸秆还田同秋季耕翻深施肥结合,可以大幅度减少春玉米农田土壤氨挥发损失。试验测定期间,春施肥各处理的田间土壤氨挥发总量较大且处理间有明显差异,特别是秸秆直接还田春施肥处理(S3)氨挥发量最高,达30.36kg/hm2,较不施肥处理多挥发26.91kg/hm2,田间氨挥发损失占到施N肥总量的17.94%;秋施肥各处理的田间土壤氨挥发总量介于5.57~6.92kg/hm2间,田间氨挥发损失仅占施N肥总量的0.28%~1.18%,各处理间差异甚微,氨挥发损失总量极低。春施肥同秋施肥处理间比较,田间土壤氨挥发总量也存在明显差异,以秸秆覆盖间(S2、A2)差异最小,为2.65kg/hm2,以秸秆直接还田间(S3、A3)差异最大,为25.58kg/hm2,氨挥发损失增加了1.77%~17.06%。     

苜蓿草地与苜蓿-作物轮作系统土壤微生物量与土壤轻组碳氮研究

从2000年10月到2004年4月，通过大田试验研究了半干旱黄土高原地区，苜蓿草地、苜蓿-作物轮作农田以及常规耕作农田中土壤有机碳、土壤全氮、土壤微生物生物量与土壤轻组物质的变化规律。结果表明，土壤轻组有机碳和氮含量苜蓿-作物轮作系统高于苜蓿草地。土壤微生物量碳和氮，以及它们占土壤有机碳和土壤全氮的比苜蓿-作物轮作系统高于常规耕作农田。土壤呼吸商苜蓿-作物轮作系统低于苜蓿草地和常规耕作农田。14年生苜蓿草地土壤微生物含量高，分解腐化植物碎片的能力高，但土壤有机物质利用不经济，3年中土壤全氮含量并无显著增加，这说明该系统较高的物质循环能力仅维持高的土壤肥力，而不能继续提高土壤肥力。苜蓿-作物用地系统不但能克服长时间种植苜蓿造成的物质循环的浪费，而且维持了良好的土壤肥力，促进了土壤氮素的有效利用。     

麦稻两熟地区不同埋深对还田秸秆腐解进程的影响

为探讨稻麦两熟地区还田秸秆的腐解进程,用尼龙网袋法研究了麦稻秸秆不同埋深(0、7、14.cm)对还田秸秆腐解及C/N比的影响。结果表明,在麦田,埋深14.cm的秸秆腐解速度最快,覆盖在表层较慢。稻田由于有水层的作用和高温高湿的环境,秸秆腐解比麦田快,覆盖在表层比埋入土中的略慢。麦季稻秸覆盖还田一季后秸秆残留率在60%左右,埋入土中的残留率在40%左右;稻季麦秸覆盖还田一季后秸秆残留率在25%左右,而埋在土中的残留率在20%左右。随着还田秸秆的腐解,秸秆含氮量逐渐增加,全碳含量下降,秸秆C/N比降低。麦季稻秸覆盖C/N比较高,而稻季麦秸覆盖的C/N比较低。一季后麦田稻秸的C/N比平均在30左右,稻田麦秸在15以上,比土壤腐殖质的C/N比高,说明种植一季作物后,还田的秸秆尚未完成腐殖化过程。     

Soybean yield as affected by crop rotations, deep tillage and irrigation layout on a hardsetting Alfisol

The hardsetting surface of many Alfisols in Australia is a limiting factor in crop production. Better soil management systems are required to improve productivity. This study reports the effects of several untested management systems, involving the combined effects of tillage (deep ripping (Rp), deep mouldboard ploughing (Mb) and disc ploughing (Disc)), irrigation layout (permanent beds, border ditch) and crop rotation treatments (single cropping (SC), double cropping (DC) and pasture (P)) on soil structure and the production of irrigated soybeans (Glycine max, L.) on a hardsetting Alfisol. It was conducted under a system of controlled traffic near Trangie, New South Wales, Australia. The DC and P treatments increased total water entry and soil organic carbon. Soybean leaf water potential (LWP) improved, and soybean yield was increased by as much as 58%. The retention of cereal and P stubble apparently enhanced total water entry by slowing the rate of irrigation water advance and by reducing the potential for slaking. The increases in soil water were associated with a reduction in soil strength; a key limiting factor in crop growth on hardsetting Alfisols. Deep tillage or the use of permanent beds did not affect soybean yields under the conditions reported in this paper, although the combination of disc ploughing and furrow irrigation was successful.     

Effects of tillage systems in dryland farming on near-surface water content during the late winter period

Tillage systems modify, at least temporarily, some of the physical properties of soil, such as soil porosity. Tillage also has an indirect effect on soil water content throughout the growth cycle, particularly in areas with a Mediterranean climate. This paper presents the results of monitoring the water content in the topsoil (0–0.20 m) of three adjacent plots during February to May cycles starting in 1994–1995 and ending in 1998–1999. Each of the plots had a surface area of 2700 m², an 8% slope and Calcic Cambisol soil. Starting in 1994, three different tillage systems were applied: conventional tillage, which is typical of the area (CT); minimum tillage (MT); and no-tillage (NT). Two vertical 200 mm TDR probes were permanently installed in each plot and measurements were taken every week. The results show that, under an NT system, the soil had significantly higher water content than the other two soil plots. However, this increased quantity of water did not denote increased crop production; on the contrary, these preliminary data point to a decrease in crop production.