Water Transfer Model Of Agroforestry System And Its Water Ecological Characteristics

Based on the water transfer theories of SPAC, experimental and simulations studieswere conducted for analyzing the water ecological characteristics of the Apple-wheatinter-cropping in the hilly area of TaiHang Mountain. According to the analysis results,the field water regulating measures were discussed. Scientific theoretical basis forimproving the integrated techniques of agroforestry were proposed, and also someprogress were made to the water ecological theories and SPAC water transfer simulationunder the non-uniform surface condition. The main trials were carried out during thewinter wheat growth stage from joint to maturity. The apple tree was planted at 4mbetween rows and 3m within the rows in 1992 , the wheat was sowed at 20cmbetween two tree rows . The main results were as follows:1. Experimental results on roots The spatial and temporal distribution characteristics of fine roots of wheat and appletree were analyzed in order to provide the basic documents for constructing the model ofwater uptake by roots and to analyze the water ecological characteristics of theinter-cropping qualitatively . The main results showed that : (1) the wheat roots systemwere characterized with densely and sparsely distributed zone vertically , belongingto 0-40cm and 40-80cm soil depth respectively;the closer to the tree row and thehigher wheat fine root density , the filling stage was the turning point in the wheatroot growth;(2) the apple fine roots concentrated at the 0-80cm soil depth where theamount of the fine root accounted for 94.33% of the total;the amount of the fineroot in the wheat zone and the tree land accounted for 60.29% and 39.71% of the totalrespectively.2. Water transfer model Two models of water transfer in the inter-cropping and sole crop field (CK) weredeveloped in order to provide the dependable methods for estimating transpirationfrom apple and wheat, soil evaporation , water uptake by roots and soil water content . Thedeveloped models were reasonable by being verified with the experimental data.3. Water ecological characteristics Transpiration from apple and wheat, water uptake by roots and soil water content ofthe inter-cropping and CK were estimated by applying the well-verified models , and thenwater ecological characteristics were analyzed quantitatively compared with CK. Themain results showed that: (1) The inter-cropping had significant efficiency of decreasingpotential and actual transpiration from wheat , and the efficiency value was 18.0% and16.78% respectively;The averaged ratio of actual transpiration between wheat andapple tree was 1.72 in actual area from joint to maturity, So the total water consumptionthrough transpiration were dominated by wheat in the inter-cropping;(2) Therelationship between the water uptake by wheat roots and the distance from the tree rowhad always showed parachute trends from joint to maturity. As for the averagedagainst the whole stage, this trend was more significant, and the maximum happened at thecenter between the tree rows;the relationship between the water uptake by apple roots andthe distance from the tree row had always showed very significant parachute trends, themaximum happened at the zone of 0-40cm from the tree row;the amount of water byapple roots in the apple zone and the wheat zone covered for 47.61% and 52.39% of thetotal respectively;The ratio of water uptake by roots between the wheat and apple was81.98 in roots mixed zone, so the wheat would be dominant absolutely in competing forwater with apple directly;(3) The relationship between the soil water and the distancefrom the tree row always showed parachute trends from joint to maturity., and themaximum had been always at the Center;Compared with CK ,the efficiency of soil waterhad been positive before the wheat filling stage , and had been negative after that, Butthe general was positive, So, this inter-cropping could not deteriorate the fieldenvironment. (4) It was feasible that the apple-wheat inter-cropping were constructed inthe hilly area of TaiHang Mountain according to the above results .4. Regulation measures on field waterThe regulation measures on field water such as optimizing the structure,instructing the efficient water-saving irrigation schedule and managing the field water inthe tree-crop interface were discussed.5. Constructive statement of this studyTwo-dimension model on water transfer of inter-cropping was developed , whichprovided use reference for studying on the model of estimated the consuming water ofagroforestry system.