【作者】 王少先；

【导师】 陈英旭； 梁新强；

【作者基本信息】 浙江大学 ， 环境工程， 2011， 博士

【摘要】 施肥影响周围环境。稻田土壤碳氮磷迁移转化受施肥影响,进而影响水体和大气等环境。本研究利用两点野外稻田定位试验(一点连续27年和另一点连续6年),对稻田土壤有机碳(SOC)固定、剖面土壤全氮(STN)和土壤无机氮(SMN)变化、剖面土壤全磷(STP)和Olsen-P变化及剖面土壤脲酶和中性磷酸酶活性分布等进行了研究,同时分析了稻田田面水和100 cm深地下水氮磷浓度,探讨了稻田氮磷径流和淋溶流失潜能。主要结论有：1.施肥影响耕层SOC含量和100 cm土体SOC密度。南昌点连续27年试验后结果表明,施肥提高了耕层SOC含量。嘉兴点连续6年试验后结果表明,施用尿素影响耕层SOC含量较小,但低剂量尿素损耗SOC；施用猪粪显著提高耕层SOC含量。南昌试验点,100 cm土体SOC密度变幅从73.1至91.4 Mg C ha-1.与CK比较,施肥同样提高了SOC密度,且有机无机肥配施处理其提高效果大于仅施化肥处理。嘉兴试验点,尿素处理组的100 cm土体SOC密度变幅从120.0到125.1 Mg Cha-1；猪粪处理组的从121.7到133.0 Mg C ha-1.嘉兴试验点,尿素处理组SOC密度差异较小,但低剂量尿素损耗SOC密度；SOC密度随猪粪用量增加而提高。两试验点的SOC密度与有机肥输入碳相关。有机无机肥配施和施用有机肥能促进土壤固碳。有机无机肥配施是高效可持续固定SOC的措施。2.施肥影响耕层STN和SMN含量,对耕层以下没有影响。STN.SMN.NH4+-N及NO3-N之间极显著正相关。南昌试验点,施肥提高了耕层STN,有机无机肥配施处理STN显著高于对照和仅施化肥处理。嘉兴试验点,尿素处理组耕层STN处理间较小,但低剂量尿素损耗土壤氮素；猪粪处理组STN随猪粪用量增加而显著提高。SMN变化趋势与STN基本相同。施用有机肥和有机无机肥配施,保持耕层土壤氮。3.施用磷肥提高耕层STP和Olsen-P,对耕层以下没有影响。南昌试验点,NK比CK处理耕层STP和Olsen-P耗竭更甚,有机无机肥配施比仅施无机磷肥显著提高耕层STP和Olsen-P.嘉兴试验点,耕层STP和Olsen-P随磷肥用量增加而增加。4.施肥提高耕层土壤脲酶活性,对耕层以下没有影响。脲酶活性随深度而降低。脲酶活性与STN.SMN.NH4+-N及NO3-N之间显著正相关。南昌试验点,有机无机肥配施提高效果优于仅施化肥。嘉兴试验点,尿素提高耕层土壤脲酶活性,但尿素过量会抑制其活性；猪粪提高效应大于尿素。施用有机肥和有机无机肥配施提高耕层土壤脲酶活性。5.施肥影响耕层土壤中性磷酸酶活性,对耕层以下没有影响。中性磷酸酶活性随深度而降低。中性磷酸酶活性与STP、Olsen-P显著正相关。南昌试验点,施肥提高耕层土壤中性磷酸酶活性,有机无机肥配施提高效果优于仅施化肥,而PK处理土壤中性磷酸酶活性低于对照。嘉兴试验点,过磷酸钙降低耕层土壤中性磷酸酶活性；猪粪提高土壤中性磷酸酶活性。施用有机肥和有机无机肥配施提高耕层土壤中性磷酸酶活性。6.水稻生长季末采样发现,田面水氮磷浓度施肥处理间有差异,但100 cm深地下水氮磷浓度无显著差异。稻田水氮磷浓度与相应土层土壤氮磷含量、土壤脲酶活性、磷酸酶活性之间显著正相关。土壤脲酶和磷酸酶活性在稻田氮磷流失潜能起着一定作用。南昌试验点,水稻生长季末采样发现,施肥提高田面水氮磷浓度,有机无机肥配施处理田面水氮磷浓度显著高于对照和仅施化肥处理,但田面水NO3--N浓度随有机肥施用量增加而减少。嘉兴试验点,水稻生长季末采样发现,尿素提高田面水氮浓度,低剂量尿素降低田面水氮浓度；猪粪提高田面水氮浓度,并随猪粪用量增加而显著提高,但田面水NO3--N浓度随有机肥施用量增加而减少。嘉兴试验点,水稻生长季末采样发现,过磷酸钙和猪粪都显著提高田面水磷浓度。7.稻田是可持续的湿地生态系统,其中的作物、微生物和土壤具有吸收、转化和吸附养分的作用,可处理消纳有机肥。稻田有田埂围栏,产生的只是机会径流,控制得当可做到零径流甚至负径流,将不会产生氮磷流失。长期耕作后稻田形成紧密犁底层,阻止水分、养分等下移,几乎不会导致氮磷淋失。稻田湿地生态系统在正确管理措施下,比如恰当施肥和零排水,可以消纳有机肥替代化肥。但不适当管理可能使稻田成为面源污染源。更多还原

【Abstract】 Fertilization affects surrounding environment. The transformation of paddy soil carbon, nitrogen, and phosphorous is influenced by fertilization, which thus impacts the surrounding water body, atmosphere, and so on. Two field fertilization experiments, one for 27 years and the other for 6 years, were selected as study materials. The main objectives of this research were:(1) to study soil organic carbon (SOC) sequestration, the changes of soil total nitrogen (STN), soil mineral nitrogen (SMN), soil total phosphorous (STP), and Olsen-P in the profile; (2) to investigate the distribution of soil urease activity and neutral phosphatase activity in the profile; and (3) to determine the concentration of N and P in paddy water under different fertilization. The followings were the main results.1. Fertilization influenced SOC content in the plow layer and SOC density in the top 0-100 cm depth soil layer. At Nanchang site after 27 years experiment, fertilization increased SOC content in the plow layer compared to CK. At Jiaxing site after 6 years experiment, urea influence SOC content in the plow layer gently, and a low rate of urea depleted SOC; pig manure (PM) markedly increased SOC content in the plow layer. At Nanchang site, SOC density in the 0-100 cm depth soil layer ranged from 73.1 to 91.4 Mg C ha-1. Soil organic C density of all the fertilizer treatments was greater than that of the CK. Those treatments that combined both chemical fertilizers and organic amendments had greater SOC densities compared to those only receiving chemical fertilizers. At Jiaxing site, SOC density in the 0-100 cm depth soil layer varied from 120.0 to 125.1 Mg C ha-1 in the urea treatments, and from 121.7 to 133.0 Mg C ha-1 in the PM treatments. Urea was not beneficial to sequester SOC. Soil organic C density increased with increasing rate of PM. At two experimental sites, SOC density was closely correlated to the input C from organic amendments. Carbon sequestration in paddy soils could be obtained by fertilization with organic amendments. Fertilization combined both chemical fertilizers and organic amendments is an effective sustainable practice to sequester SOC. 2. Fertilization affected STN and SMN in the plow layer, but not under the plow layer. There were significant correlations among soil total N, SMN, NH4+-N and NO3--N. At Nanchang site, STN of treatments with fertilizers was greater than that of the CK without fertilizer. Those treatments that combined both chemical fertilizers and organic amendments had greater increasing effects on STN compared to those only receiving chemical fertilizers. At Jiaxing site, urea gently affected STN in the plow layer, and a low rate of urea depleted STN; PM significantly sequestered STN. The change trend of SMN was similar to STN. Fertilization with organic amendments can maintain paddy soil N.3. Phosphorus fertilization increased STP and Olsen-P in the plow layer but not under the plow layer compared to P-free fertilization. Downward movement of P was not observed. At Nanchang site, STP and Olsen-P in the plow layer was exhausted more in the NK than in the CK. Those treatments that combined both chemical fertilizers and organic amendments had greater increasing effects on STP and Olsen-P compared to those only receiving chemical fertilizers. At Jiaxing site, superphosphate and PM significantly increased STP and Olsen-P in the plow layer, and the effect increased with increasing P rates.4. Fertilization influenced soil urease activity in the plow layer but not under the plow layer. Soil urease activity decreased with increasing soil depth. Soil urease activity was positively and significantly correlated with STN, SMN, NH4+-N, and NO3--N. At Nanchang site, soil urease activity of treatments with fertilizers was greater than that of the CK without fertilizer. Those treatments that combined both chemical fertilizers and organic amendments had greater increasing effects on soil urease activity compared to those only receiving chemical fertilizers. At Jiaxing site, urea increased soil urease activity in the plow layer, and an excessive rate of urea inhibited soil urease activity; PM had greater increasing effects on soil urease activity compared to urea. Fertilization with organic amendments increased soil urease activity in the plow layer.5. Fertilization affected soil neutral phosphatase activity in the plow layer but not under the plow layer. Soil neutral phosphatase activity decreased with increasing soil depth. Soil neutral phosphatase activity was positively and significantly correlated with STP and Olsen-P. At Nanchang site, soil neutral phosphatase activity of the treatments with fertilizers was greater than that of the CK without fertilizer, but except PK treatment. Those treatments that combined both chemical fertilizers and organic amendments had greater increasing effects on soil neutral phosphatase activity compared to those only receiving chemical fertilizers. At Jiaxing site, superphosphate decreased soil neutral phosphatase activity in the plow layer; PM increased soil neutral phosphatase activity in the plow layer. Fertilization with organic amendments increased soil neutral phosphatase activity in the plow layer.6. At the end of rice season, fertilization affected N and P concentration in paddy surface water but not in paddy groundwater at a 100-cm depth. The N and P concentration in paddy water were significantly and positively correlated to soil N and P, soil urease activity, and neutral phosphatase activity in the corresponding soil layer. Soil urease activity and neutral phosphatase activity contributed to the loss potential of paddy N and P. At Nanchang site at the end of rice season, fertilization increased N and P concentration in paddy surface water. Those treatments that combined both chemical fertilizers and organic amendments had greater increasing effects on N and P concentration in paddy surface water compared to those only receiving chemical fertilizers, but NO3--N concentration in paddy surface water decreased with increasing rate of organic amendments. At Jiaxing site at the end of rice season, urea increased N concentration in paddy surface water, but a low rate of urea decreased N concentration in paddy surface water; PM increased N concentration in paddy surface water, but N03--N concentration in paddy surface water decreased with increasing PM rate. At Jiaxing site at the end of rice season, both superphosphate and PM markedly increased P concentration in paddy surface water.7. Paddy fields are sustainable wetland ecosystems. The paddy wetland ecosystem may act as a sink for C, N, and P through plants and soil apart from being a pollution source due to the existence of barriers and plow pans. The plants and soil are the reservoirs for nutrients in the paddy system, barriers on the paddy perimeter prevent runoff, and plow pans prevent leaching. Paddy wetland ecosystem can act as a sink especially for organic amendments, which could partly or totally substitute for chemical fertilizers, with proper management such as reduced-drainage or zero-drainage taking the advantage of the barriers. If with improper management, paddy fields may become non-point pollution sources.更多还原