Study On Integrated Technologies For Improving Crop Water Productivity

In the paper, a scientific and practical technical integration system for improving crop water productivity is introduced on the basis of study on optimal integration of multiple single technique.The study focuses on improving crop water productivity under the condition of water resources shortage, taking system theory and optimization theory as the guidance and crop physio-ecological responding mechanism under soil water stress as the condition, on the basis of a lot of field test of the related technique of water conservancy, agriculture, biology, chemistry and management under the system framework, with crop growing as time series and satisfying crop physiological growth demand as the condition, the said technical integration system has been verified in agricultural production, having created satisfied effect.In chapter 1, the concept of crop water productivity, influencing factors, the principal technique for improving crop water productivity and developing trend of water productivity in China and in the world are introduced. The characteristic of the technique for improving crop water productivity, the involved fields and theory and significance of study on improving crop water productivity are described. On the basis of analysis and summarizing of the current status of domestic and overseas study on the technique of improving crop water productivity, proposals on issues to be further studied and the direction for the study are put forward and the principle of the study, the technical consideration and component of study are outlined.In chapter 2, the basic conditions and representativeness of the experimental area, the principal experimental procedures and utilization of experiment data are introduced.In chapter 3, crop physio-ecological response under water stress and the method for determining water stress threshold value is studied. (1) A thorough study is made on the response mechanism of such principal physio-ecological indices as the stomata, resistance, transpiration intensity, photosynthetic rate, the rate of being in the milk, the yield component and crop water productivity of winter wheat and summer corn under water stress. It is found out that there is threshold value for winter wheat and summer corn physio-ecological indices in key growing period responding to water stress. The threshold value is stable, however, the water stress threshold value of summer corn is more dispersive than winter wheat and summer corn is more sensitive to water stress. (2) The conception of optimal partitioning clustering method, the mathematical model and its solution are introduced. The method is used in calculation of crop water stress threshold value for the first time.(3) The water stress threshold value of winter wheat and summer corn are analyzed and determined on the basis of the field experimental data of Changgeand Gongyi experimental areas in 1999 and 2000, providing theoretical basis for working out and optimizing irrigation strategy.In chapter 4, crop water production functions model and the variation regulation of water sensitive index are studied. ? The concept and definition of crop water production functions sftitic model and dynamic model and the whole growing season model and growing period model are introduced. (2) A study is made on the adaptability of such four principal water production functions models as Jensen, Stewart, Blank and Singh, by using the long series data of winter wheat from 1991 to 1996 at the Huibei experimental station in Kaifeng. (3) The parameters of water production functions model of winter wheat and summer corn of whole growing season and growing period in plain area of Henan are studied and determined by using the text data from 1999 to 2000 in Changge and Gongyi and the reorganized test data of irrigation in Henan, providing model parameter support for optimization of irrigation technique design. @ It is found out in the study that the water sensitive index variation between years has regularity. In more dry year, the sensitive index is greater, while in more wet year, the sensitive index is smaller. The result of further study indicates that the crop water sensitive index is related to ETo — the atmospheric dry degree, on the basis of which the power function relationship between crop water sensitive index and TEo is established, providing important theoretical support for application of sensitive index.In chapter 5, the mathematical model of deficit irrigation practice , the modifying method of the model parameters and the principal crop deficit irrigation practices are studied and the field test verifying results are introduced. ? In the study, the principle of balanced pumping of ground water in the area where groundwater is the sole water source is put forward. When annual crop water consumption of the irrigation area are similar, the overyear gross output value of the irrigation area is highest. The said principle provides theoretical basis for overyear optimal allocation of groundwater. (2) A two-level coordination model for optimal allocation of the irrigation district water resource among different crop and different growing period is introduced. In the model, taking water resource allocation in crop growing season as the first level and water resource allocation among different crop as the second level. The irrigation water consumption is related with crop yield to realize optimal utilization of water resource of the whole irrigation district that could not be solved by separate consideration. The model has been verified with the field experimentation data and has been proved reasonable. (3) The further study result indicates that the method of determining the model parameters would influence the accuracy of the calculation result, that should be improved. In the study the concept of "norm crop coefficient" is put forward. The index relationship between the soil water stress and soil water content is set up, having improved the reliability of calculation result of the actual evapotranspiration under soil, water stress. The relative error of the model is controlled below 5%.@ The deficit irrigation program of principal crops in plain area of Henan is worked out on the basis of field test data.In chapter 6, the adaptability of water saving irrigation engineering technique is assessed and the water saving technique that are suitable for agricultural production in plain area of Henan under the current productivity development level are introduced. ? By absorbing the advantages of domestic prevailing methods for assessment of water saving irrigation engineering, the recursive level structure for comprehensive evaluation index system of water saving irrigation engineering technique is studied and introduced. The said index system involves the most indices and most scales so far in China. (2) An entropy-weight model for system fuzzy comprehensive evaluation is set up for the first time on the basis of engineering fuzzy set theory and entropy-information theory. The subjective weighting method and objective weighting method are combined to comprehensively determine the weighted index, having overcome the shortcomings of the method mainly depending on subjective experience and judge in the past, and avoided the influence of artificial factors on determination of weight, so as to make the system fuzzy comprehensive evaluation result to be more realistic. (3) The quantification method for qualitative index is difficult in semi-structural or non-structural system optimization or evaluation. In the paper, Telphy method and dualistic fuzzy relative comparative law are combined for quantifying of qualitative index, solving the problems such as the existing quantification method for qualitative index being difficult to integrate effectively many person's opinions and discordant between the quantification value of qualitative index and quantitative index value that could not be used in comprehensive evaluation of a large system.@The model is used for comprehensive appraisal of five water saving irrigation technique applied in groundwater irrigation district in plain area of Henan. The micro irrigation belt combined with low pressure pipe for water distribution or improved border (furrow) irrigation technique is suitable to be developed in the experimental area. The results of on-farm experimentation, field investigation and inquiry to farmers demonstrate that the above conclusion tallys with the present rural irrigation practice and economic development level in plain area of Henan.In chapter 7, the experimental study on individual agronomic practice for improving crop water productivity is described.? The field drought resistant test have been made on 10 corn varieties and 6 wheat varieties that are grown in Henan for selection of the most suitable varieties. The test result indicates that the corn of Zhengdan 958 and wheat of Yumai 34 having better biological characteristic, being suitable for growing in water deficit area. (2) In view that the domestic research suggests applying more nitrogenous fertilizer and using less phosphate fertilizer, a special study is made on making the best of water and phosphate fertilizer. The study result indicates that phosphate fertilizer has dual effect of promoting plant growing and increasing water depletion, and appropriate application of water and phosphate fertilizer will promote corn or wheat absorbing more nutrient and potassium and its transport up to the ground. At the same time, transport of moisture from inside of the plant to line blade or moisture transportations is controlled. Therefore, the crop capacity for moisture preserving is improved. Under drought condition, the effect of phosphate fertilizer is difficult to be gained, however, if water and phosphate are applied appropriately after a short time of drought, crop growing may be promoted andcrop yield could be increased and water use efficiency could be improved through coordinating plant growing and promoting dry matter accumulation. (3) Study is made on deep-plowing between crop lines. Compared with traditional tillage practices, the deep plowing could increase soil porosity, make the loose soil bed thicker, improving soil moisture capacity and moisture fertilizer supply to crop root, creating better soil structure, extending the nutrition scope and creating suitable condition for crop root growing.? Study is made on evaporation control with chemical method. Implementation of suitable chemical control measures could make biological properties of plant more harmonious and rational to get the effect of preserving moisture and restricting transpiration. (§) The study is made on crop water requirement and water consumption under the effect of mulching and chemical control measures for water saving. No report of such study result is found. The study result indicates that under the condition of controlling evapotransporation with mulching of crop stalk and chemical control measures for water saving, the crop yield could increase by 5% and water requirement could cut down by7% or so. This is real water saving. It is also found out in the study that under the condition of controlling evapotransporation, the variable relationship between crop yield and water requirement is not linear. However, the water saving and yield increment mechanism needs to be studied further.In chapter 8, an innovative study is made on irrigation managerial organizations.? The irrigation managerial organizations and irrigation management status have been analyzed. The conception of SIDD and PIM and their application in irrigation districts in China have been reviewed and summarized. Those two management mode have not touched on the issues of water right and property right.? The three principles of management science, the characteristic of management organizations, water right and water market system and the organizing and design principles are analyzed.? Taking improving crop water productivity as the aim, village level irrigation management as a managerial level, water right and water resource utilization right as fundamental issue, fanners participation as the basic practice, the innovative idea of design framework for village level irrigation management organization in plain area groundwater irrigation district and the corresponding government management framework, the related suggestion and notable issues are also described.In chapter 9, the comprehensive study is made on technique of improving crop water productivity and the field test verifying is described. ? An integrated, high -efficient, scientific and practicable technical system is put forward on the basis of the study which takes improving crop water productivity and cutting down water resources consumption as the target, using system theory and optimization theory, combining the features of water conservancy, agriculture, biology and management science and individual technique. In the technical system, multiple individual technique have been optimized and integrated under the system framework, with crop growing stages as time series and taking satisfying the needs of crop physiological growth as the essential conditions.? The integrated technical system for improving crop water productivity have been verified in field test. The experimental result indicates that compared with conventional cultivation systemunder the integrated technical system water consumption of summer corn and winter wheat cut down by 9% and 15%, respectively, the yield of corn and wheat decrease by 3.8% and 6.4% respectively, the corn water productivity reaches 1.98 kg/m3, the winter wheat water productivity reaches 1.74kg/m3, 5.3% and 10.1% higher than that under conventional cultivation system.? The economic index of the integrated system is analyzed and assessed. In the calculation period, the benefit-cost ratio is 1.73, the internal rate of return is 18.4%, showing that the economic benefit is remarkable. In the period of 2001-2002, the integrated technical system of improving crop water productivity were popularized in a large area of Shigu town, Changge city.In chapter 10, the major research results described in the paper is summarized, pointing out the characteristic and innovation of the research results, and giving the suggestions for further study.