作 者 ：苏朋,傅昱,何艳,徐建明,吴建军,吴良欢
期 刊 ：植物营养与肥料学报 2014年 20卷 6期 页码：1431-1440
关键词：水肥管理；氮素转化；酸度矫治；秸秆还田；低产水稻土；
Keywords:water-fertilizer management, N transformation, acidity remediation, straw returning to field, low yield paddy soil,
摘 要 ：【目的】在华中低产酸化黄泥田双季稻区,研究不同温度、水分条件及施肥对添加微生物促腐菌剂下秸秆腐解过程中土壤氮素转化和酸度矫治的影响。【方法】采用室内培养试验,于15℃和35℃条件下,设2个水分条件[40%和100%最大田间持水量(WHC)]及2种氮肥处理(尿素、猪粪),动态监测水稻秸秆腐解过程中土壤无机硝态氮(NO-3-N)、 铵态氮(NH+4-N)和总水溶性氮(TDN)含量,以及土壤pH变化在105 d培养周期内的变化特征。【结果】温度与各形态氮含量及土壤pH间均缺乏相关性,不同温度下水分、 氮肥类型对氮转化及pH影响大致相同; 35℃和15℃条件下几乎整个培养周期内,各处理铵态氮含量表现为WHC40%+U >WHC40%+M >WHC100%+U >WHC100%+M,即尿素处理优于猪粪处理(P<0.01),不论添加何种氮素均表现为WHC40% >WHC100% (P<0.01);NO-3-N和TDN含量顺序为WHC100%+U >WHC100%+M >WHC40%+U >WHC40%+M,其中后二者NO-3-N含量无差异,WHC100%条件下NO-3-N和TDN含量均显著高于40% WHC(P<0.05); 氮净矿化量为WHC40%+U >WHC100%+U,添加猪粪处理后在两水分条件下都为负值,表现生物固定,而净硝化强度为WHC100%+U >WHC100%+M,低水分含量的两氮肥添加均表现弱硝化;各处理至培养结束时土壤pH均大幅提升,pH值大小呈WHC40%+M >WHC40%+U >WHC100%+M >WHC100%+U,净变化值则分别为+0.35、 +0.51、 -0.61和+0.15,其中,WHC100%+M处理虽然最终表现有0.61单位降低,但在前期仍有大幅上升的现象。【结论】高温度、 水分含量下,施尿素可因其短期内氮矿化与pH(高净氮矿化量、 净硝化量、 酸度提升)方面的优势而作为田间推荐的水肥耦合管理措施;微生物在氮素循环中对设定的温度条件有一定适应能力;相比于尿素在改变各种氮浓度和诱导pH变化方面的良好作用,猪粪从供氮时效方面讲,是一种可采用的但也相对难以利用的氮源。
Abstract:【Objectives】The impacts of soil water content, fertilization incorporated with addition of decay-facilitating microbial incolua on the N transformation and soil acidity remediation were investigated in low yield acidified yellow-paddy soil in double rice cropping area, central China. 【Methods】An incubation experiment involved by decay-facilitating microorganisms was respectively performed at 15℃ and 35℃ in laboratory for 105 days to evaluate impacts of soil water content [40% and 100% of water holding capacity (WHC)] and N fertilizer (urea and manure). The soil inorganic nitrate (NO-3-N), ammonium (NH+4-N)), total dissolved nitrogen (TDN) and changes of pH were monitored periodically. 【Results】Data showed that water content and N fertilizer exhibited similar effects on N transformation and pH variance when soils were incubated by two kinds of temperatures, 35℃ and 15℃, and ammonium contents in soils were orderly classified into four levels by WHC40%+U > WHC40%+M > WHC100%+U > WHC100%+M across the entire incubation period (P<0.01) regardless of N fertilizer, but the contents of nitrate and TDN in treatments were all in orders of WHC100%+U > WHC100%+M >WHC40%+U >WHC40%+M. The contents of nitrate and TDN reatments under WHC100% were increased significantly comparing with those under WHC40% (P<0.05), not difference existed between fertilizer treatments. WHC40%+U showed higher net N mineralization than WHC100%+U when manure was applied, suggesting that microbial immobilization occurred in soils. Additionally, net nitrification in WHC100%+U was higher than that in WHC100%+M, but treatments incubated under WHC40% show slight nitrification; pH values are elevated in nearly all the treatments following a specific trend of WHC40%+M >WHC40%+U >WHC100%+M >WHC100%+U, with net pH variation of +0.35, +0.51, -0.61 and +0.15, respectively. Obviously, although WHC100%+U leads to great increase in pH at initial stage, but decrease the pH by 0.61 at the end of incubation. Higher temperature, water content and urea application should be recommended as an effective field management practice for satisfactory N mineralization and pH elevation. Soil microorganisms have an adaptation to temperature for N mineralization, the magnitude of C- and N- mineralization mainly depend on the availability of soil water and N resources. Manure is an applicable choice despite of supplying less N of various forms and weak affecting in pH fluctuations. 【Conclusions】An integrative manage practice in maintaining capacity of soil water content and increasing the efficiency of N fertilizer should be an effective pathway during the process of returning straws from early rice and late rice to field at the low yield paddy soils in central China.
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