全球农作物生产水利用效率地区差异分析及建议

粮食安全和水安全已成为当前全球最紧迫的问题之一。农作物生产水利用效率(CWUE)较低的国家如何提高其CWUE,减小区域CWUE差异,也成为实现区域协调发展中亟待解决的重要问题。本文结合87个国家1990-2007年的相关数据,基于随机前沿生产函数构建并估计了CWUE模型;在洲间、洲内和全球各国间三维度对CWUE差异进行方差分解,并分析差异及其因素值的变化情况、差异因素的贡献份额及其变化情况;列出各区域内部CWUE较低的国家现时改善CWUE、减小区域CWUE差异时应关注的重要因素,包括该区域(各洲或全球范围)内CWUE差异的最主要贡献因素、波幅较大或波幅不断变大的因素、以及贡献份额波动幅度较大或波幅不断变大的因素;通过情景分析验证了改善最主要贡献因素对减小CWUE差异的效果,展示了在改善最主要贡献因素后各区域为进一步减小CWUE差异应重点关注的因素;最后,本文对提高CWUE的具体措施提出了相关政策建议,包括改善全要素生产率、要素结构相对不合理的国家优化生产要素投入等。

修正灌溉水利用效率指标体系的研究

建立科学的灌溉水利用效率指标体系有助于准确评价灌溉水的利用效率,从而为节水灌溉项目决策及灌溉管理提供科学的依据。本文分析了目前灌溉水利用效率指标体系存在的问题,并作了系统的修正,提出了由渠道水利用效率、渠系水利用效率、田间水利用效率、作物水利用效率和灌区灌溉水利用效率组成的灌溉水利用效率指标体系,并分别给出了这些指标的定义及计算方法。

Water Use and Growth in Three Populations of Red Cedar （Cedrela odorata L.） and Associated Crops in Mexico

The association between the growth and water-use efficiency in three populations of C. odorata in Veracruz Mexico （La Antigua, Misantla and Catemaco） from two agroforestry system sites was studied, one in association with corn and another with pipiain. TRP （transpiration）, gs （stomatal conductivity）, CO2A （CO2 assimilation）, WUE （water use efficiency）, height, coverage and stem diameter were measured. The populafon of La Antigua associated with pipian presented the highest WUE （7.13 μmol CO2 m2-sl/mmol H20 m2.sl）, while the population of Catemaco reached high values （10 μmol CO2 m2 sl/mmol H20 m2-s1） in the site associated with corn, the populations established with corn presented a great growth in height and stem diameter. Based on the physiological responses and growth of the studied populations, the towns of La Antigua and Catemaco may be recommended for the establishment of commercial plantations.

Impacts of climate change on agricultural water resources and adaptation on the North China Plain

Climate change is having a considerable impact on the availability of water resources for agricultural production on the North China Plain （NCP）, where the shortage of water is currently disturbing the stability and sustainability of agricultural production with respect to the drying tendency since the 1950s. However, although potential evapotranspiration （ET） has shown a decreasing trend under climate change, actual ET has slightly increased with an acceleration in hydrological cycling. Global climate model （GCM） ensemble projections predict that by the 2050s, the increased crop water demand and intensified ET resulting from global warming will reduce water resources surplus （Precipitation-ET） about 4%-24% and increase significantly the irrigation water demand in crop growth periods. This study assesses possible mitigation and adaptation measures for enabling agricultural sustainability. It is revealed that reducing the sowing area of winter wheat （3.0%-15.9%） in water-limited basins, together with improvement in crop water-use efficiency would effectively mitigate water shortages and intensify the resilience of agricultural systems to climate change.

Late Season Sugarcane as Affected by Deficit Irrigation at the Yield Formation Stage in Northern Ivory Coast

A field trial was carried out in Ferk6 2 Sugar mill located in northern Ivory Coast, in order to study sugarcane growth and yield response to deficit irrigation imposed over the yield formation stage. The crop used was a first ratoon Co 957, a non flowering late season sugarcane variety. The experiment was completely randomized following a one-factor design with 4 water deficit treatments in 3 replicates. It came out that the optimum water deficit treatment reached 20%, i.e., 80% of crop water requirements were satisfied through irrigation. That treatment gave 7.9 kg cane/m3 or 0.98 kg sugar/m3 as irrigation water use efficiency. Relatively low crop growth rates （0.2-0.4 cm/day） as well as low cane yields （24.5-78.4 t/ha） were obtained as a result of an intensive and persistent dry season occurred over the yield formation stage. In line of prevailing climatic conditions, cane juice quality measured was particularly high on Co 957 which used to be a moderately performing variety in Ferk6 2 sugar mill.

Water Consumption of Seven Forage Cultivars under Different Climatic Conditions in the North China Plain

The objectives of this study were to determine the characteristics of water consumption of seven forage cultivars, ryegrass （Secale cereale L.）, triticale （×Triticosecale Wittmack）, sorghum hybrid sudangrass （Sorghum biolor× Sorghum Sudanense c.v.）, ensilage corn （Zea mays L.）, prince’s feather （Amaranthus paniculatus L.）, alfalfa （Medicago sativa L.）, and cup plant （Silphium perfoliatum L.）, in response to climate variability （especially precipitation）. Field experiments were conducted at Yucheng Integrated Experiment Station from 2005 to 2009. Fifteen irrigated lysimeters were used to measure evapotranspiration （ET） and crop coefficient （Kc） of these seven forage varieties under ample water supply. The mean Kc for alfalfa is 1.08, and the mean Kc for other forage varieties ranges from 0.79 to 0.94. Kc for hibernating forage is higher in wet years than that in dry years, followed by normal years, while for annual forage, Kc is higher in dry years than in normal years, and is the lowest in wet years. For perennial varieties the order is normal years, dry years, and wet years. Among the annual varieties, ensilage corn is the first choice due to its highest average forage N yield and water use efficiency （WUE）. Sorghum hybrid sudangrass is another forage cultivar that grows well under all climatic conditions. It can achieve 1.08-2.31 t ha-1 y-1 N yield under all circumstances. Prince’s feather is sensitive to climate change and its N yield dropped below half even when ample water was applied in dry and normal years. Ryegrass and triticale have the advantage of growing in the fallow phase after cotton is harvested in the North China Plain （NCP） and the latter performed better. For perennial varieties, alfalfa performed better than cup plant in dry years. With ample irrigation, alfalfa can achieve higher biomass and WUE under arid climate condition, but excessive rain caused reduction in production.