不同水氮管理对梨园土壤氨挥发的影响

Effects of different water and nitrogen management on ammonia volatilization in pear orchard soil

根际注射施肥在果树种植上应用广泛,但目前注射施肥及配套灌溉管理对果园氨挥发的影响尚不明确。本文于2019年3—9月在河北省晋州市果园示范基地进行,利用动态箱法分析了梨树追肥时期不同水氮管理下土壤氨挥发速率和损失量的变化规律。试验设置5个处理:不施肥(CK)、氮肥表面撒施+常规灌溉(BW1)、注射施肥+常规灌溉(IW1)、氮肥表面撒施+节水灌溉(BW2)、注射施肥+节水灌溉(IW2)。结果表明,各处理各时期氨挥发基本在施肥后1 d达到峰值,在5~10 d后结束。BW1、IW1、BW2、IW2氨挥发损失量差异均达显著水平(P<0.05),分别为24.05 kg·hm^(−2)、8.43 kg·hm^(−2)、31.94 kg·hm^(−2)和14.06 kg·hm^(−2);与传统管理(BW1)相比注射施肥处理(IW1和IW2)减排率分别达64.95%与41.54%。撒施处理氨挥发受灌溉量影响较大,根际注射施肥可以显著降低氨挥发的排放,且受灌溉量影响较小。相关分析表明,氨挥发与土壤铵态氮含量和pH呈正相关,与硝态氮含量呈负相关,且与铵态氮和硝态氮的相关性均达到极显著水平(P<0.01);土壤水分与铵态氮呈正相关且达极显著水平(P<0.01)。与传统管理方式相比,根际注射施肥与节水灌溉结合是减少果园氨挥发的有效途径之一。

Conventional pear tree fertilization and management results in fertilizer waste,environmental contamination and other problems.The long-term goal of farmland managers is to use soil water and fertilizers efficiently to improve crop yield.In this study,the dynamic box method was used to analyze changes in the soil ammonia volatilization rate,loss,and the physical and chemical properties under different water and nitrogen management regimes in the pear topdressing period in the orchard demonstration base of Jinzhou City,Hebei Province,from March to September 2019.The experiment had five treatments:blank(CK,no fertilization with conventional irrigation),compound fertilizer broadcasting and conventional irrigation(BW1),rhizosphere injection(20 cm deep)of liquid fertilizer and conventional irrigation(IW1),compound fertilzer broadcasting and 70%conventional irrigation(BW2),rhizosphere(20 cm deep)injection of liquid fertilizer and 70%conventional irrigation(IW2).The volatilization of ammonia in each treatment was the most severe in the first four days after fertilization.Two treatments of compound fertilizer broadcasting(BW1 and BW2)were especially severe,the peak variation range was 1.5−7.5 kg·hm^(−2)·d−1.Two treatments of rhizosphere injection of liquid fertilizer(IW1 and IW2)steadily changed with time,the peak range was 0.1−5.0 kg·hm^(−2)·d−1.The volatile loss of ammonia in the BW1,IW1,BW2,and IW2 treatments was 24.05 kg·hm^(−2),8.43 kg·hm^(−2),31.94 kg·hm^(−2),and 14.06 kg·hm^(−2),respectively;compared with BW1(traditional management),the emission reduction rates of rhizosphere injection of liquid fertilizer(IW1 and IW2)was 64.95%and 41.54%,respectively.Ammonia volatilization was significantly affected by the irrigation amount,and rhizosphere injection fertilization significantly reduced ammonia volatilization emission and was less affected by the irrigation amount.Correlation analysis showed that ammonia volatilization was positively correlated with the soil ammonium nitrogen content and pH,but negatively correlated with the soil nitrate nitrogen content.The correlation between ammonium nitrogen and nitrate nitrogen was highly significant(P<0.01).Soil moisture was positively correlated with ammonium nitrogen content(P<0.01).Compared with traditional management methods,the combination of rhizosphere injection fertilization and water-saving irrigation is an effective way to reduce nitrogen loss in orchards.