Effect of Straw Mulching on Change of Evaporation and Water-Salt in the Saline Soil

In 2009,a field experiment was conducted at the Pucheng Lubotan Experimental Station in Shaanxi province to determine the dynamic change law of straw mulching quantity on saline soil evaporation,water content and salt content.The straw mulching quantity had four levels of 1.05,0.75,0.45 and 0.15 kg/m2,non-mulching(C0) was controlled trial.The results indicated that the daily average evaporation under the four different straw mulching quantity were 1.335 8,1.310 3,1.035 7,0.629 0 mm/d,respectively,significantly higher than that of C0.The soil water content of every soil layer was gradually increased with the time,change range of soil water content was maximum in the 10 cm soil layer,soil water content were 9.280%,9.000%,6.920% and 2.450%,respectively,significantly higher than that of C0.The soil salt content of 10,30 cm soil layers were gradually decreased with the time,salt was gradually suppressed in the 50 cm soil layer,change range of soil salt content was maximum in the 10 cm soil layer,soil salt content were 0.811%,0.802%,0.723% and 0.381%,respectively,significantly lower than that of C0.When straw mulching was 0.75 kg/m2,and then increased the amount of straw,the role of water retention and inhibited salt accumulation was not significantly enhanced.Using straw to cover soil surface is an effective measure to reduce soil water evaporation loss,to improve water use efficiency,to inhibit surface accumulation of the salt,to improve the utilization of arable land,and the straw mulching quantity of 0.75 kg/m2 is preferable for Lubotan area.