北京山地绿化树种引进效果及其土壤保育功能研究

对北京市石佛寺浅石山区引进绿化树种的适应性及长期以来对土壤养分元素的影响效果开展研究,结果表明,引进树种长势均匀,取得了良好成效,混交林、乔灌草结合的配置模式对土壤氮、磷、钾和有机质的改善作用明显。固土能力较强的是桧柏、沙地柏,分别是17.816 t/(hm2.a)和17.796 t/(hm2.a),混交林固土能力比纯林要强,黄栌+荆条配置模式的单位面积保肥价值是黄旗松+云杉保肥价值的1.71倍。价值量从大到小排序为:黄栌+荆条>黄柏+白蜡+元宝枫>桧柏>五角枫>华北落叶松>黄栌+五角枫+侧柏>沙地柏>油松>黄栌>白皮松>楸树>侧柏+山杏>黄旗松+云杉。可见,森林保肥能力既和固土能力有关,也与其林地土壤中的营养元素含量有密切关系。     

利用电容式传感器连续监测土壤硝态氮质量分数的试验研究

通过室内和田间试验,研究土壤硝态氮质量分数与电容式传感器监测的土壤电导率、含水率和温度的定量关系。在室内以NH4NO3分析纯为溶质,进行了溶液质量浓度0～10g/L的7次土柱试验;在2009年和2010年春玉米生育期内监测了不同滴灌水量条件下土壤电导率、含水率和温度动态变化。结果表明,土壤电导率能较好的反映土壤硝态氮质量分数的变化;土壤硝态氮质量分数与电导率、含水率和温度之间的关系可用二次多项式描述,且3个土壤参数对土壤硝态氮质量分数的影响均达到了极显著水平(P≤0.01);由于回归模型的拟合精度受土壤初始养分盐分质量分数及空间变异等因素的影响,为获得较高的预测精度,应进行田间标定。     

Heterogeneity in farmers’ production decisions and its impact on soil nutrient use: Results and implications from northern Nigeria

Sustainable use (in terms of nutrients) of soil resources by farmers in Sub-Saharan Africa is constrained by institutions and markets. This paper explores the case of northern Nigeria, by using a combination of multi-attribute utility theory and bio-economic modelling. This approach allowed us to identify heterogeneity in production strategies and to quantify its effect on the use of soil nutrient resources.We find that farmers with larger land holdings place more emphasis on gross margins in their utility function, while those with larger holdings of fertile fadama fields place more emphasis on sustainability. Risk aversion, operationalised through variance minimization, appears an important attribute in the utility function of many farm households that are more dependent on agriculture for their overall income.A regression analysis shows that differences in production strategies significantly affect nutrient balances, but also shows that such effects are heterogeneous across locations. We find more favourable nutrient balances for some of the more market-oriented farm households who place more emphasis on sustainability. In farm plans of the most risk-averse households, the production of cereals for subsistence consumption dominates and leads to negative soil nutrient balances, especially for potassium.Farmers who place a large importance on gross margins are likely to benefit most from policies aimed at enhancing profitability through improving functioning of markets. The large group of risk-averse farmers will have the largest immediate gain in utility from policies and technologies aimed at reducing production risk in high-value crops. Additional policies aimed at creating a stronger market-oriented production by the least-endowed farm households could play a role in reducing intensity of soil fertility mining. Under these conditions, the efficient cropping pattern shifts partially from cereal cropping to high-value crops, associated with higher input use.The main results are similar to those in other studies, although some of the nutrient balances are less negative. The results do appear to be sensitive to the type of cropping activities included in the analysis, and additional methodological research is required. Extensions of the used method should further account for temporal and spatial differences in soil fertility, leading to differences in nutrient uptake and production, as well as potential temporal heterogeneity in production strategies.     

微咸水灌溉下土壤水盐动态及对作物产量的影响

华北平原农业灌溉用水非常紧缺,水资源日益缺乏与粮食需求日益增多之间的矛盾尖锐。充分利用微咸水资源是缓解这一矛盾的重要途径之一。该文以中国农业大学曲周试验站1997－2005年冬小麦和夏玉米微咸水灌溉田间长期定位试验为基础,研究了充分淡水、充分淡咸水、关键期淡水、关键期淡咸水和不灌溉等5个处理下土壤饱和电导率和含盐量的动态变化,探讨了微咸水灌溉对冬小麦和夏玉米产量的影响。结果表明：土壤水盐动态呈受灌溉和降雨影响的短期波动和受季节更替影响的长期波动;在正常降雨年份,使用微咸水进行灌溉是可行的,不会导致土壤的次生盐渍化;微咸水灌溉虽然导致冬小麦和夏玉米产量降低10%～15%,但节约淡水资源60%～75%。如果降雨量达到多年平均水平以及微咸水灌溉制度制订合理,微咸水用于冬小麦/玉米田间灌溉前景广阔。     

Exploring options for water savings in lowland rice using a modelling approach

Water-saving irrigation regimes are needed to deal with a reduced availability of water for rice production. Two important water-saving technologies at field scale are alternately submerged–nonsubmerged (SNS) and flush irrigated (FI) rice. SNS allows dry periods between submerged soil conditions, whereas FI resembles the irrigation regime of an upland crop. The effects of these regimes on the water balance and water savings were compared with continuously submerged (CS) and rainfed (RF) regimes.The crop growth model ORYZA2000 was used to calculate seasonal water balances of CS, SNS, FI, and RF regimes for two locations: Tuanlin in Hubei province in China from 1999 to 2002 during summer seasons and Los Baños in the Philippines in 2002–2003 during dry seasons. The model was first parameterized for site-specific soil conditions and cultivar traits and then evaluated using a combination of statistical and visual comparisons of observed and simulated variables. ORYZA2000 accurately simulated the crop variables leaf area index, biomass, and yield, and the soil water balance variables field water level and soil water tension in the root zone.Next, a scenario study was done to analyse the effect of water regime, soil permeability, and groundwater table depth on irrigation requirement and associated rice yield. For this study historical weather data for both sites were used.Within seasons, the amount of irrigation water application was higher for CS than for any of the water-saving regimes. It was found that groundwater table depth strongly affected the water-yield relationship for the water-saving regimes. Rainfed rice did not lead to significant yield reductions at Tuanlin as long as the groundwater table depth was less than 20 cm. Simulations at Los Baños with a more drought tolerant cultivar showed that FI resulted in higher yields than RF thereby requiring only 420 mm of irrigation.The soil type determined the irrigation water requirement in CS and SNS regimes. A more permeable soil requires around 2000 mm of irrigation water whereas less permeable, heavy soil types require less than half of this amount. We conclude that water savings can be considerable when water regimes are adapted to soil characteristics and rainfall dynamics. To further optimize water-saving regimes in lowland rice, groundwater table dynamics and soil permeability should be taken into account.     

Water resources and water use efficiency in the North China Plain: Current status and agronomic management options

Serious water deficits and deteriorating environmental quality are threatening agricultural sustainability in the North China Plain (NCP). This paper addresses spatial and temporal availability of water resources in the NCP, identifies the effects of soil management, irrigation timing and amounts, and crop genetic improvement on water use efficiency (WUE), and then discusses knowledge gaps and research priorities to further improve WUE. Enhanced irrigation and soil nutrient (mainly nitrogen) management are the focal issues in the NCP for enhancing WUE, which are shown to increase WUE by 10-25% in a wheat-maize double cropping system. Crop breeding has also contributed to increased of WUE and is expected to play an important role in the future as genetic and environmental interactions are understood better. Agricultural system models and remote sensing have been used to evaluate and improve current agronomic management practices for increasing WUE at field and regional scales. The low WUE in farmer's fields compared with well-managed experimental sites indicates that more efforts are needed to transfer water-saving technologies to the farmers. We also identified several knowledge gaps for further increasing WUE in the NCP by: (1) increasing scientific understanding of the effects of agronomic management on WUE across various soil and climate conditions; (2) quantifying the interaction between soil water and nitrogen in water-limited agriculture for improving both water and nitrogen-use efficiency; (3) improving irrigation practices (timing and amounts) based on real-time monitoring of water status in soil-crop systems; and (4) maximizing regional WUE by managing water resources and allocation at regional scales.     

四川盆地丘陵区土壤水分的动态及其随机模拟

土壤水分动态的研究是定量理解植被对水分胁迫响应、土壤养分循环的水文控制、植物水分竞争等生态系统动态的关键,是目前国内外的研究热点。利用2004年-2007年每天的土壤水分监测数据,结合laio土壤水分动态随机模型,研究了四川盆地丘陵区(重庆铜梁虎峰)土壤水分的动态特征及其laio模型在亚热带气候条件推求土壤随机动态特征的适用性。结果表明：监测年内各层土壤水分无论在枯水年还是平水年均差异显著,其中连续平水年土壤水分的含量和变异系数均高于枯水年,枯水年后的平水年低于枯水年;土壤水分的季节变化可分为稳定期、消耗期、波动期;土壤水分的垂直变化来看,土壤水分含量并非完全随着土壤深度的增加而增加。用laio概率随机模型导出的土壤水分概率密度图表明：各层土壤水分的峰度出现在=0.5左右,变化幅度较宽。用laio模型导出的土壤水分峰度和变幅与观测的概率密度函数结果基本一致,相对误差在5%,laio模型可用于分析亚热带气候下土壤水分动态随机特征。     

An optimization model for zero-excess phosphorus management

Livestock production in the 21st century is moving in the direction of higher animal densities. Accompanying livestock expansion is the challenge of manure handling and utilization. A model for zero-excess phosphorus (ZEP) management has been developed for a dairy-crop operation that is based on multicriteria optimization. ZEP management practices are identified by simultaneously minimizing excess manure phosphorus, feed cost, and cropland requirement. System components include commercial fertilizer application, feed crop production, P storage in the soil profile, surface runoff, procurement of feed supplements, ration formulation, dairy herd structure and dynamics, manure handling, manure storage, and manure spreading. Manure is recycled as a fertilizer nutrient source in crop production. ZEP management practices include a cropping system, nutrient applications, and animal rations which are characterized by low feed cost and maximum use of land resources.     

Time-variable soil hydraulic properties in near-surface soil water simulations for different tillage methods

Simulating near-surface soil water dynamics is challenging since this soil compartment is temporally highly dynamic as response to climate and crop growth. For accurate simulations the soil hydraulic properties have to be properly known. Although there is evidence that these properties are subject to temporal changes, they are set constant over time in most simulations studies. The objective of this study was to improve near-surface soil water simulations by accounting for time-variable hydraulic properties. Repeated tension infiltrometer measurements over two consecutive seasons were used to inversely estimate the hydraulic properties of a silt loam soil under different tillage - conventional (CT), reduced (RT), and no-tillage (NT). Simulated water dynamics with constant and time-variable hydraulic parameters were compared to observed data in terms of the soil water content and water storage in the near-surface soil profile (0-30 cm). The measurements indicate a considerable temporal variability in the saturated hydraulic conductivity, the field-saturated water content and the parameter α of the van Genuchten/Mualem model. Temporal variability was largest for CT and RT, whereas under NT, replicates of measured water contents and hydraulic properties showed a considerable large spatial variability. Simulations with time-constant hydraulic parameters led to underestimations of soil water dynamics in winter and early spring and overestimations during late spring and summer. The use of time-variable hydraulic parameters significantly improved simulation performance for all treatments, resulting in average relative errors below 13%. Since simulation results agreed with observed water dynamics in two seasons, the applicability of inversely estimated hydraulic properties for soil water simulations is demonstrated. Thus, simulations that address applied questions in agricultural water management may be improved by using time-variable hydraulic parameters. The simulated water balance indicated that RT and NT result in better water storage than CT and therefore may increase water efficiency under water-limited climatic conditions.     

四翅滨藜在河北省内陆平原盐碱地区的引种试验研究

以四翅滨藜为研究对象,分别在沦州市孟村回族自治县、衡水市武邑县和枣强县选取重度、中度和轻度盐碱荒地为试验试区,分析盐碱地条件下土壤水分、盐分动态变化过程与植物生长关系及植株生长、养分特性.通过2005-2007年3个年度的试验数据分析,结果表明,四翅滨藜生长期具有明显的耐旱特性,植株耐旱性苗期小于发育期.试验年度试区土...     

春小麦调亏灌溉对土壤钾素养分的影响

对河西绿洲灌区春小麦调亏灌溉2年后的土壤速效钾和全钾的变化进行了研究,并用配对样本t检验(双尾检验)对小麦收获时土壤钾素养分指标年际间的差异、土壤全钾与速效钾及其与全生育期调亏供水量间的关系进行了分析。结果发现,春小麦调亏灌溉对土壤钾素养分有明显影响,2004年小麦收获时0~20、20~40、0~40cm土层全钾、速效钾均显著低于2003年。回归分析发现,调亏灌溉春小麦收获时0~20 cm土层全钾和速效钾与小麦全生育期供水量呈线性正相关,0~20 cm和0~40 cm土层速效钾也随着全钾的增加呈显著线性增加的趋势。     

Sustainable agriculture: A case study of a small Lopez Island farm

Overreliance on fossil fuel based inputs, and transport of inputs and products is seen by many as a threat to long-term agricultural and food system sustainability. Many organic, biodynamic, and low-input farmers limit off-farm inputs, attempting instead to farm within the carrying capacity of their land or local environment. These farmers often accept lower farm productivity because they see reduced reliance on non-renewable inputs as more sustainable. Documentation of low-input agricultural systems through both replicated research trials and case studies is needed in order to better understand perceived and real advantages and tradeoffs. The goal of our study was twofold: (1) to compare liming and biodynamic (BD) preparations in improving pasture on a moderately acidic pasture soil through stimulation of soil microbial activity; (2) to place these findings within the context of a whole farm analysis of economic, plant, and animal health. Treatments included lime, the Pfeiffer Field Spray plus BD compost preparations, and untreated controls. Soil pH, total C and N, microbial activity, forage biomass, and forage quality were evaluated over two growing seasons. Both lime and the Pfeiffer Field Spray and BD preparations were only moderately effective in raising soil pH, with no effect on soil microbial activity or forage yield. Lime significantly reduced forage crude protein but the practical implications of this are questionable given the overall low quality of the forage. While the farm is profitable and economically stable and the animals healthy, the need for future targeted nutrient inputs cannot be ruled out for sustainable long-term production.     

土壤养分随地表径流流失机理与控制措施研究进展

降雨条件下坡面土壤养分伴随水土流失而流出田块,不仅降低土壤肥力,而且引起水环境污染。从坡面养分迁移机理、数学模型模拟、控制措施3个方面对国内外学者在坡面养分随地表径流迁移过程的研究进展进行回顾。坡面养分迁移机理研究主要包括降雨特征、土壤特性、坡面特征、化学物质特征、耕作与施肥方式、地表覆盖及管理控制措施等因子对坡面养分迁移的影响作用。数学模型主要包括经验模型、基于物理过程的理论模型。物理基础模型基本上是在假设养分传递内在机制基础上建立的,包括混合层理论、对流扩散作用、雨滴击溅作用、水流冲刷作用等。考虑到我国土壤侵蚀现象严重,坡面养分迁移过程受到土壤侵蚀作用的影响,因此针对防治土壤侵蚀而提出了一些相关的控制养分迁移的措施。同时,对目前研究中存在的问题以及进一步需要深入研究的内容进行了说明。     

Effects of untreated and treated wastewater irrigation on some chemical properties of cauliflower (Brassica olerecea L. var. botrytis) and red cabbage (Brassica olerecea L. var. rubra) grown on calcareous soil in Turkey

The use of wastewater for irrigation is increasingly being considered as a technical solution to minimize soil degradation and to restore nutrient content of soils. The aims of this study were to test if wastewater irrigation could improve soil fertility without affecting the quality of soils and plants. A field experiment was conducted in 2006 to investigate the effects of irrigation with untreated, and preliminary and primary treated wastewater on macro- and micronutrient distribution within the soil profile, yield and mineral content of cauliflower and red cabbage plants grown on a calcareous Aridisol in eastern Anatolia, Erzurum province, Turkey. Wastewater irrigation affected significantly soil chemical properties in the 0–30 cm soil layer and plant nutrient content after harvest. Application of wastewater increased soil salinity, organic matter, exchangeable Na, K, Ca, Mg, plant available phosphorus and microelements, and decreased soil pH. Wastewater irrigation treatments also increased the yield as well as N, P, K, Ca, Mg, Na, Fe, Mn, Zn, Cu, Pb, Ni and Cd contents of cauliflower and red cabbage plants. The highest yield, macro- and micronutrient uptake of cauliflower and red cabbage plants were obtained with the untreated wastewater. Undesirable side effects such as heavy metal contamination in soil and plant, and salinity were not observed with the application of wastewater. It can be concluded that untreated wastewater can be used confidently, in the short term, in agricultural land, while primary treated wastewater can be used in sustainable agriculture in the long term.     

Soil water content and water balance in rainfed fields in Northeast Thailand

Northeast Thailand has a semi-humid tropical climate which is characterized by dry and rainy seasons. In order to stabilize crop production, it may be necessary to develop new water resources, such as soil moisture and groundwater, instead of rainfed resources. This is because rainfed agriculture has already been unsuccessfully tried in many areas of this region. In this study, we investigate the soil water content in rainfed fields in Khon Kaen in Northeast Thailand, where rice and sugarcane were planted, over a 1-year period that contained both dry and rainy seasons, and estimate the actual evapotranspiration (ET_a) using micrometeorological data. In addition, we assess the water balance from the results of the soil water content investigation and the actual evapotranspiration. Although the soil water content at depths above 0.6 m in both the lower and the sloping fields gradually decreased during the dry season, the soil water content at a depth of 1.0 m was under almost constant wet conditions. Two-dimensional profiles of the soil water content demonstrated that at the end of the dry season, the soil layers below a depth of 0.4 m showed a soil water content of more than 0.10-0.15 m³ m⁻³, thus suggesting that water was supplied to the sugarcane from those layers. The range in ET_a rates was almost the same as that in the previous study. The average ET_a rates were 3.7 mm d⁻¹ for the lower field and 4.2 mm d⁻¹ for the sloping field. In the dry season, an upward water flow of 373 mm (equivalent to a flux of 1.9 mm d⁻¹) was estimated from outside the profile. The source of this upward water flow was the sandy clay (SC) layer below a depth of 1 m. It was this soil water supply from the SC layer that allowed the sugarcane to grow without irrigation.     

Heterogeneity in land resources and diversity in farming practices in Tigray,Ethiopia

The management of soils is an important issue for policy makers in Ethiopia. However, most of the interventions designed to conserve the soil resources have fallen short of the expectations, performing impressively in the short run, but proving unsustainable on a long-term basis. There are no simple explanations for the failure of these interventions to reverse soil degradation, but it has been evident for some time that there is an uneasy connection between ‘objective’ assessments of the state of the land and the way this information is used in the policy-making processes. It is now widely accepted that understanding the processes of the soil degradation is not simply a matter of analysing changes in the stock of physical and nutrient capital. While studies of nutrient balances are an important component of research in soil erosion and land degradation, their results need to be considered in the context of social, cultural and political factors.     

日光温室油桃节水灌溉试验研究

临夏州降水量稀少,水资源匮乏,为了提高水资源利用率,实行节水灌溉,在该地区进行了日光温室油桃节水灌溉试验研究,研究了滴灌与沟灌技术在生育期内对土壤含水率、作物的生育动态以及产量的影响。结果表明,滴灌比沟灌平均节水1251 m3/hm2,"92-1"品种在滴灌条件下比沟灌每株增产5.9 kg,每公顷增产29475 kg,日光温室反季节油桃栽培应选择滴灌节水技术。为了取得较好的经济效益,应采用滴灌最优灌溉制度。     

Irrigation management for corn in the northern Great Plains, USA

Irrigation management influences production costs and affects leaching of nutrients to groundwater. This study was conducted to compare irrigation scheduling techniques on a field-scale site and to determine whether significant irrigation water savings and equivalent yields could be achieved compared with the practices of other commercial growers in the local area. The effects of four irrigation scheduling techniques on seasonal irrigation water requirements and corn grain yields were studied for the 1990–1995 seasons at a field-scale (53.4 ha) site within the Oakes Test Area (OTA) of the Garrison Diversion Unit in southeastern North Dakota, USA. The four scheduling techniques, applied with field quadrants and seasons as dimensions of a modified Latin square statistical design, included irrigating based on tensiometer and infrared canopy temperature measurements, two water balance methods, and irrigating based on CERES–Maize estimates of plant-extractable soil water. No statistically significant differences in seasonal irrigation totals were found between irrigation scheduling methods or irrigation quadrants, while statistically significant differences were found for season. Corn grain yield was significantly affected by seasons, quadrants, and irrigation scheduling methods for both the current and previous seasons. Compared to other commercial growers in the OTA, this study maintained 5% higher yields and saved approximately 30% in irrigation inputs. Careful irrigation scheduling, based on any of the four techniques, offers the potential to reduce input costs for irrigated corn production in the area. Received: 3 February 1999     

Potassium carryover dynamics and optimal application policies in cotton production

Information about soil nutrient carryover dynamics can assist cotton producers with the optimal management of potassium (K) fertilizer. Optimal K management promotes cotton plant health, may decrease input costs, and increases cotton lint yields. A dynamic programming model was developed to determine optimal K application rates and economic returns under different soil information scenarios based on cotton yield response to K fertilizer and fertilizer carryover estimates from a multi-year field trial. A Monte Carlo analysis was conducted to simulate the impact of stochastic input and lint prices and cotton yield on K management over a five-period planning horizon. Results suggest that soil test data could provide important information about K carryover potential, which may lead to more efficient fertilizer use and higher profit margins for cotton producers.     

基于GIS、RS的滴灌棉田土壤养分精确管理分区研究

在GIS和RS支持下,针对新疆生产建设兵团第五师81团滴灌棉田,选用遥感结合土壤、土壤、遥感数据为数据源,利用模糊c均值聚类法进行土壤养分精确管理分区研究。研究结果表明:无论以何种数据源划分分区,分区后各分区养分指标变异系数均有所下降,空间分布朝均一方向发展;不同管理分区间差异明显,同一管理分区内土壤养分含量的空间变异差异较小。以遥感结合土壤为数据源所划分管理分区与实际产量所划分分区符合度最高达到91.36%,以土壤为数据源的管理分区次之,符合度达到84.40%,仅以遥感数据(归一化植被指数)为数据源所划分管理分区符合度最低为75.47%。因此,运用聚类分析法以遥感结合土壤数据为数据源可获得较好的分区结果,可实施变量投入和精确施肥推荐,为棉田土壤养分管理提供科学的理论依据。