مرکز منطقه ای اطلاع رساني علوم و فناوري - تاثير ماده شيميايي پلي اكريل آميد بر تلفات خاك و نفوذ آب در خاك در روش آبياري جويچه اي

چكيده لاتين :

Practice of furrow irrigation in agricultural lands that are susceptible to erosion and having high slope causes problems such as soil loss and low infiltration rate. Above mentioned problems reduce soil fertility and productivity and prevent achieving optimum irrigation efficiency. Recent field studies demonstrated that the small concentration of polyacrylamide (PAM) dissolved in irrigation water appreciably increased infiltration rate and reduced soil losses from irrigated furrows. In order to study the effect of this material, an experiment was carried out employing factorial method in block design at the agricultural research station, University of Tehran. The experiment included three levels of inflow rate (0.6, 0.8 and 1 Ps) and three levels of PAM (5ppm, 10ppm and control) in triplicate on a soil. Soil type was silty loam having 1.3% slope. Furrow length was about 140 m with a 0.75 in spacing. In this study, two irrigation were applied. In the first irrigation, two different rates of PAM (5 and 10 ppm) were added to the stream flow with especial arrangement, then the effect of PAM on soil erosion and infiltration was investigated. In the second irrigation, the stream flow was without PAM, therefore, only the effect of added PAM on the first irrigation on soil erosion and infiltration was followed. In 5ppm treatment, PAM was added continuously to the stream flow until the stream flow reached to the end of furrow (advance time), then it was intermittently added to inflow water with half an hour intervals. In 10ppm treatment, the duration of addition of PAM was two times of advance time and its application discontinued thereafter. The results showed that addition of 10ppm PAM was suitable for soil loss reduction and infiltration increment. Using 10ppm PAM in irrigation water reduced furrow soil losses by 87% and increased furrow infiltration rate by 46% as compared to the control treatment. In the second irrigation which was without the addition of PAM, furrow soil loss was reduced by 55% as compared to control treatment. The result of statistical analysis also showed that the effect of PAM at 10ppm level with inflow rate of 0.6 1/s on soil loss reduction and the same level with the inflow rate of 1 lls on the improvement of infiltration was significant at 5% level.