Evaluation of Subsurface Drainage Design Based on Projection Pursuit

Abstract

Soil salinization is a type of soil degradation, which is one of the biggist problems in protected agriculture. A welldesigned subsurface drainage system with reasonable drain space and depth contributes to large ratio of desalination and high crop yield. For selecting the optimization design, it is important to find out how the subsurface drainage systems affect the soil conditions and improve the harvest. In this experiment, the drainage pipes were arranged by two different patterns, the dynamics of surface soil EC was measured by salinity sensors, and the tomato yield was calculated. In order to comprehensively evaluate the rationality of subsurface drainage system, a PP(projection pursuit) model was also established. The results showed that the monthly variation of subsurface soil EC was in a trend of decline in general, drainage treatment Tr1 and Tr2 performed much better than non-drainage treatment CK. Based on the model's calculations, drain spacing 8m and drain depth 0.7m(Tr2) was selected as the preferable subsurface drainage parameter. The desalination ratio of Tr2 was 9.59% larger than CK, and 1.7% larger than Tr1; tomato yield of Tr2 reached 38796.5kg/hm2, which was 31889.9kg/hm2 higher than CK, and 6823kg/hm2 higher than Tr1.