JWSS - Journal of Water and Soil Science

Increasing crop production per unit volume of water consumption requires recognizing the most dependent variable in drip irrigation to the volume of water consumption and also identifying the most important variables independent of water productivity in surface and subsurface drip irrigation for optimal use of available water resources. The present research was carried out in Behbahan Agricultural Research Station during four cropping seasons (2013-2017) on a Kabkab date variety. Experimental treatments include the amount of water in the subsurface drip irrigation method based on two levels of 75% and 100% water requirement and in surface drip irrigation based on 100% water demand. Data were analyzed using a randomized complete block design with three replications. The results of the analysis of variance of the mean of different irrigation treatments in quantitative traits showed that the effect of irrigation was significant at the level of 1% in terms of cluster weight index, fruit weight, and fruit flesh to kernel weight ratio. The results of regression analysis of variance showed that in the dependent variable of cluster weight, the consumption water volume explained 19.1% (R2 = 0.191) of the fluctuations of the dependent variable (cluster weight). Among all the studied variables, the volume of water consumption explained the most significant changes in date cluster drying. Fruit moisture with t (2.096) and equivalent beta coefficient (0.046) had a significant positive effect on water productivity at the level of 5%. The results of the Pearson correlation coefficient showed that the effect of yield on changes in water productivity was much greater than the volume of water consumed so the yield caused significant changes in water productivity. While the effect of water consumption on water productivity was not significant.

In sustainable agriculture, cow manure is used for greater productivity, a rich source of E-Coli pathogenic bacteria. The objective of this research was to investigate the simultaneous effect of the fractionation size of cattle manure and irrigation water salinity on the retention of E-Coli bacteria in the depths of the sand column with a height of 10 cm under saturated flow. Four different particle fractions of cow manure (1-2, 0.5-1, 0.25-0.5, and smaller than 0.25 mm) were added to the surface of the sand column at the scale of 30 tons per hectare, then leaching was done with different salinities (0, 0.5, 2.5, 5, and 10 dS/m) up to 10 pore volumes, then samples were taken from the depths of 0, 3, 6, and 12 cm. The number of bacteria in each sample was determined by the live counting method. The results showed that the effect of all sources of change and their interaction effects on the retention of bacteria in the soil is significant at the level of 5%. Salinity had a negative effect on the retention of bacteria, and the highest and lowest values of the relative concentration of bacteria (the result of dividing the number of bacteria in each soil depth by the initial number of bacteria in the desired manure treatment) were in 0 dS/m and 10 dS/m salinity of leaching water, respectively. By decreasing the size of cow manure particles due to the increase in hydrophobicity and blocking of preferential pores, the retention of bacteria decreased in all investigated soil depths. The highest and lowest retention of bacteria in the soil were investigated in the largest cow manure particle size (1-2 mm) and the smallest cow manure particle size (less than 0.25 mm), respectively. In addition, the highest relative concentration of bacteria in the soil was seen in the depth of 0-3 cm, and no significant difference was seen in other soil depths.