| A field experiment was conducted during 2011 to 2015 to verify the effects of polyacrylamide(PAM) application at different growth stages of oat. PAM was applied at a rate of 75 kg·hm-2 per year. The experiment consisted of 6 treatments, i.e. conventional tillage(CK), one year PAM application(M1), two consecutive years PAM application(M2), three consecutive years PAM application(M3), four consecutive years PAM application(M4), and five consecutive years of PAM application(M5). Impact of different PAM application years on holding moisture, characteristics of water consumption, and water use efficiency(WUE) was investigated in hilly and drought farming region along the Great Wall. The results indicated that compared with CK, the application of PAM increased soil moisture in 0 to 100 cm depth, and promoted biomass accumulation of oat, but decreased the total water consumption, and raised yield and WUE of oat. Under different treatments, the soil moisture and storage capacity of M5 and M4 treatments were higher than those of other treatments at each growth stage. However, total water consumption of M5 and M4 treatments were lower, which was significant(P<0.05). There was no significant difference among M1, M2 and CK treatments. The largest impact on oat yield by soil moisture content was mainly found in 0 to 10 cm soil layer at seedling stage, 10 to 20 cm at jointing stage, 20 to 40 cm at heading stage, 0 to 10 cm at filling stage, and 10 to 20 cm and 40 to 60 cm at mature stage. At each growing stage, the water consumption of M5 treatment was significantly lower than that of M4 treatment except from sowing to seedling stage and heading to filling stage. Eventually, the highest economic benefit and WUE were found under M4 treatment, which was increased by 35.67% and 3.67 kg·hm-2·mm-1, respectively, compared to CK. Taking WUE, economic benefit and yield into account, PAM application in four consecutive years is more suitable in dry farming regions. |
基本信息
