渠灌类型区农业高效用水模式与工程示范

该文系在完成“九五”国家农业高效用水科技产业示范工程项目“渠灌类型区农业高效用水模式与产业化示范”专题研究的基础之上,结合示范区建设及运行管理等情况总结而成。在分析研究渠灌类型区农业用水存在问题的基础上,首先提出了渠灌类型区实现农业高效用水的基本思路,依据上述思路确立了提高渠灌区输水过程用水效率、田间灌溉过程用水效率与生产效率,以及提高灌区工程运行管理水平的技术与措施;其次,根据以上研究结果进一步确立了渠灌类型区农业高效用水的模式,并建立了相应的实体模型进行工程示范,初步验证和确立了这种高效用水模式。     

Irrigation Module and Sowing Date Affect Seed Cotton Yield,Quality, Productivity Indices,and Economics of Cotton in North-western India

ABSTRACT

Delayed sowing and imprecise application of irrigation water to cotton has been the major hurdle in sustaining cotton yield in north-western India. Therefore, studies were initiated to ascertain the impact of heavy or normal level of presowing irrigation (PSI), scheduling time of first postsowing irrigation (POSI) under two sowing dates (SDs) on cotton arranged in a split block design replicated thrice. PSI_h (100 mm) recorded 23.2% higher seed cotton yield over PSI_n (70 mm) owing to better yield attributes and higher stand. First POSI at 4 weeks after sowing (WAS) resulted the highest yield (3072 kg ha^?1), while one at 6 WAS (POSI₆) recorded least due to poor population and reduced yield attributes. Water productivity under POSI₆ was lesser by 29.1%, 25.2%, and 16.2% as compared to POSI₃, POSI₄, and POSI₅, respectively. April sown crop out yielded the May sown cotton crop by 939 kg ha^?1 due to better yield attributes. Nitrogen factor productivity (NFP) among SD remained higher by 23.3% for April as compared to May sowing. PSI_h exhibited better NFP over PSI_n. POSI₆ recorded least NFP by 24.4%, 28.5%, and 16.3% as compared to POSI₃, POSI₄, and POSI₅, respectively and was indicative of relatively poor utilization of N under delayed schedules. Therefore, planting in April after heavy PSI and scheduling first POSI at 4 WAS is best strategy for sustaining cotton yield and maximizing farmer profitability.     

Drip irrigation and nitrogen fertilization alter phenological development and yield of spring maize (Zea mays L.) under semi-arid conditions

Abstract

Maize response to deficit water and nitrogen for assessing phenological development and yield was studied under semi-arid conditions. Experiment consisting three drip irrigation levels, replenish 60 (DI₆₀), 80 (DI₈₀) and 100 percent (DI₁₀₀) of cumulative pan evaporation, and four nitrogen doses 50 (RN₅₀), 75 (RN₇₅), 100 (RN₁₀₀) and 125 (RN₁₂₅) per cent of recommended nitrogen. A Furrow irrigated treatment was kept as control/check. Significant earliness in visibility of collar of 8^th leaf, tasseling, silking and significant delay in dough stage and physiological maturity was recorded under well water treatment DI₁₀₀ as compared to DI₆₀. Days to collar of 8^th leaf, tasseling and silking had significant negative correlation, and duration of yield formation phase and days to physiological maturity had significant positive correlation with grain yield. Higher DM production, longer yield formation phase and late physiological maturity led to significantly higher grain yield under DI₁₀₀. In case of nitrogen levels, phonological characteristics like collar of 8^th leaf, tasseling and silking were significantly delayed, and dough stage and physiological maturity were advanced under nitrogen deficit treatment RN₅₀ as compared to RN₁₀₀ and RN₁₂₅. Significantly higher dry matter production and longer yield formation phase observed led to significant higher SCY under RN₁₀₀ and RN₁₂₅ as compared to RN₅₀. Yield formation phase was significantly longer under drip irrigated crop as compared to control during 2^nd year of study. Crop phenological development significantly affected by drip irrigation regimes and nitrogen levels, and there was significant correlation between phenological stages development and grain yield.     

作物主动汲水技术内涵与研究进展

持续创新农田灌溉技术，有利于应对农业水资源短缺、耕地资源不足，也是确保中国粮食安全的重要技术基础。该研究提出了"作物主动汲水"（Crop Initiative Draw Water，CIDW）概念，并分析其得以实现的基本条件是：土壤水非饱和性、外界水水势始终小于大气压、外界水和作物根系的距离有效性、高效的水势能差转化界面。综合文献划分出了压力势差（Pressure Potential Difference, P-CIDW)、渗透势差 (Osmotic Potential Difference, O-CIDW)和重力势差作物主动汲水（Gravitational Potential Difference，G-CIDW）等3种形式的CIDW，并分析了它们的势能特征和基本实现途径。进一步，从硬件设备技术、作物表现、水盐运移与分布、土壤生境等几个方面，重点综述了P-CIDW的研究进展。近十多年来的研究表明，相比漫灌、沟灌、滴灌等传统灌溉技术，适宜参数的P-CIDW能够显著地提高作物产量与水分利用效率、养分吸收和肥料利用率、根际土壤酶活性和微生物多样性、水肥耦合效应，明显地影响了作物生理生化指标、土壤养分有效性和养分空间分布；土壤质地及其剖面构型显著地影响了P-CIDW下的水盐运移与分布；利用初始土壤含水率和基质势、渗水器导水率、供水压力以及时间等参数，可以半机理半经验地估测P-CIDW的累积入渗量。最后展望了CIDW研究的未来，认为，土壤水分-作物关系的基础理论急需要突破、研发高效的势能转化界面材料仍然是发展CIDW技术的关键任务、尽快制定P-CIDW技术标准、P-CIDW控压方法还需要革命性的创新。     

基于水盐平衡的绿洲灌区次生盐碱化防治研究

土壤次生盐碱化是威胁新疆绿洲灌区持续发展的关键因子。以位于塔里木河流域的渭干河灌区为例,在简要分析灌区水盐运移的控制因素基础上,以水盐均衡原理为指导,深入剖析了灌区-田块-作物根系3个尺度的土地盐分均衡特点及其相互关系,重点估算了淋洗需水量,简要讨论了次生盐碱化的驱动因子,最后从政策、技术与经济方面给出了控制次生盐碱化的对策。     

温室封闭式栽培自适应灌溉方法

为了改进和提高温室封闭式栽培精细灌溉控制方法,针对利用Penman-Monteith(P-M)公式和传感器数据信息相结合进行灌溉控制中因为涉及参数较多而使用不便、需要近似计算导致建立的作物蒸腾模型精度不够等问题,该文根据封闭式栽培可以回收并循环利用多余灌溉水的特点,利用灌溉量与排出量的差值和温室小气候环境数据建立相对精确的作物蒸腾量计算模型,并在此基础上利用人工神经网络算法实现了温室封闭式栽培自适应灌溉控制,结果表明,在10 d内灌溉用水量为实际蒸腾量的97.8%,基本实现了按照作物需水量进行灌溉。研究对于实现按照作物蒸腾量进行准确的水分供给、节约灌溉用水量、提高水分利用效率具有一定的现实意义。     

波涌灌溉技术田间适应性分析

利用地面灌溉模型对波涌灌溉条件下地表水流及入渗过程进行模拟,在模拟结果与田间实测资料对比基础上,确定适宜的田间灌水参数,即土壤入渗强度、田块规格、田面坡度、入地流量、田间微地形等的变化范围,给出适合于波涌灌水方法应用的田间组合条件,提出波涌灌水技术对壤类土质的田间适应性,为制定波涌灌溉的田间实施方案提供科学的依据     

肥液浓度对单膜孔入渗NO-3-N运移特性影响的室内试验研究

该文通过室内入渗试验，研究了不同浓度的单膜孔肥液入渗NO^-₃-N的分布特性。研究表明：不同浓度的膜孔肥液入渗土壤NO^-₃-N浓度的湿润锋运移距离与土壤水分运动的湿润锋一致；肥液浓度越大，相同入渗时间的NO^-₃-N浓度锋运移距离越大，土壤剖面NO^-₃-N浓度最大值越大，相同深度处土壤NO^-₃-N浓度也越大。肥液入渗土壤NO^-₃-N浓度分布特征与湿润体深度符合分段函数模型。供水入渗过程中，NO^-₃-N浓度锋运移距离和浓度最大值均随时间的延长而增大；再分布过程中，NO^-₃-N浓度锋运移距离继续增大，而NO^-₃-N浓度最大值逐渐减小。     

Longterm influence of liquid sewage sludge on the organic carbon and nitrogen content of a furrow-irrigated desert soil

Summary In this study we evaluated the impact of five annual liquid sewage-sludge applications on the organic C and N content of a furrow-irrigated desert soil. Mineralization rates showed that sludge organic matter is mineralized rapidly (65% per year). Resistant residual sludge organic matter accumulation resulted in a theoretical increase in total soil organic C of 0.013% for the single sludge rate or 0.038% for three annual applications. These small additions were not detected in sludged soils at any depth to 270 cm. Similarly, increases in total soil N were not detected at any depth. However, soluble forms of organic C and N did increase in sludged soils relative to the non-sludged soils. In addition, soluble C:N ratios decreased significantly in the sludged soils. Soluble C and N also increased with depth due to leaching. This study therefore shows that applications of liquid sludge onto desert soils could affect the status of underground aquifers with respect to nitrate pollution.     

Photosynthetic water‐use efficiency of irrigated winter and summer crops in a typical mountain oasis of northern Oman

The millenia‐old existence of traditional, surface‐irrigated Omani mountain oases implies a remarkable sustainability of such systems in a hyperarid environment. This study was conducted in the mountain oasis of Balad Seet, situated in the Al‐Jabal‐al‐Akhdar mountains of northern Oman, to investigate the water‐use efficiency (WUE) of these oases and how farmers regulate it. In 2005, gas exchange of single leaves of 9–16 plants was measured for the most important perennial field crop alfalfa in both February and August, for the typical winter crop oat in February, and the dominating summer crop sorghum in August. The measurements were conducted five times a day in subplots irrigated the evening before and in the surrounding control plots, where plants had been withheld from irrigation for 14–16 d. Water deficit at the end of the irrigation interval reduced the stomatal conductance (g_s) strongly in summer alfalfa, oat, and sorghum, but only slightly in winter alfalfa. In oat, the reduction of net photosynthetic rate (P_N) at the end of the irrigation cycle was caused mainly by stomatal closure, in sorghum by nonstomatal factors and in summer alfalfa by both, whereas P_N in winter alfalfa remained unaffected. The ratio of net photosynthetic rate to stomatal conductance (P_N/g_s), the “intrinsic water‐use efficiency”, increased in all investigated crops in response to drought because of a stronger reduction of g_s than of P_N. This increase was small in winter alfalfa, but much stronger in oat, sorghum, and summer alfalfa. The data indicate that alfalfa maintains a relatively high CO₂ assimilation rate year‐round, contributing to a relatively high annual dry‐matter production. The decrease of the light intensity in the late afternoon caused by the shading effect of the surrounding mountains diminishes the crop evapotranspiration in the oasis.