The combined application of organic fertilizer and chemical fertilizer is an effective measure to increase nutrient content of soil plough layer, which must have a profound impact on the deep soil nutrients, especially the contents of nitrogen forms. The purpose of this study was to explore the characteristics of soil nitrogen forms in plough layer and along depth gradient in different fertilization treatments, so as to evaluate the soil quality in spatial dimension, further provid ing a theoretical basis for scientific fertilization and improvement of paddy soil fertility. Here, a 34-year field experiment was conducted with three treatments: without any fertilizer (CK), pure chemical fertilizer (NPK) and chemical fertilizer combined with organic fertilizer (NPKM). We analyzed the content of nitrogen forms in 0 - 100 cm soil depth and their ratios to total nitrogen (TN), and discussed the correlation between nitrogen forms contents and pH, CEC. Results showed that, compared with CK, both NPK and NPKM significantly increased the contents of nitrogen forms in topsoil (soil layer of 0 - 20 cm), especially nitrate nitrogen (NO<sub>3</sub><sup style="margin-left:-6px;">-</sup>-N) content increased by 70% (NPK) and 111% (NPKM), respectively. Although the contents of different nitrogen forms decreased gradually along soil depth gradient, NPKS slowed down the decline rate of TN and alkali-hydrolysable nitrogen (AN) in 0 - 60 cm soil layer, compared to CK. Compared to NPK, NPKM significantly increased the NO<sub>3</sub><sup style="margin-left:-6px;">-</sup>-N/TN ratio in 0 - 20 cm soil layer, but also decreased the content of -N in 20 - 40 cm, which was beneficial to reduce the risk of nitrogen leaching caused by nitrate leaching into deep layer. The increase of soil pH in NPKM treatment obviously alleviated the problem of soil acidification caused by long-term application of chemical fertilizer. Correlation analysis showed that there was a significant positive correlation between soil nitrogen forms and cation exchange capacity (CEC), but no significant correlation with soil pH. In conclusion, NPKM ensured the nutrients of soil plough layer (0 - 20 cm), also reduced the risk of nitrogen infiltration and nitrogen loss, thus ensur ing the fertility of soil profile.
KeywordsLong-Term FertilizationSoil Depth GradientTotal NitrogenNitrogen Form
Cai, H.C. (2000) Present situation and Development Prospect of Rice production in China. China Rice, 6, 5-8.
Wang, D., Ye, C., Xu, C., Wang, Z., Chen, S., Chu, G. and Zhang, X. (2019) Soil Nitrogen Distribution and Plant Nitrogen Utilization in Direct-Seeded Rice in Response to Deep Placement of Basal Fertilizer-Nitrogen. Rice Science, 26, 404-415. https://doi.org/10.1016/j.rsci.2018.12.008
Dong, Y., Yuan, J., Zhang, G., Ma, J., Hilario, P., Liu, X. and Lu, S. (2020) Optimization of Nitrogen Fertilizer Rate under Integrated Rice Management in a Hilly Area of Southwest China. Pedosphere, 30, 759-768. https://doi.org/10.1016/S1002-0160(20)60036-4
Zhang, G., Li, J., Xu, M. and Gu, S. (2009) Effects of Chemical Fertilizer and Organic Manure on Rice Yield and Soil Fertility. Scientia Agricultura Sinica, 42, 543-551.
Nan, Z., Liang, B., Chen, Y., Liu, S. and Liu, J. (2016) Effect of Long-Term Fertilization on Soil Nitrogen Mineralization and Crop Yield. Acta Agriculturae Boreali-Sinica, 31, 146-151.
Ma, L., Yang, L., Yan, T., Wang, J., Li, D. and Yin, S. (2010) Profile Distribution and Mineralization Characteristics of Nitrogen in Relation to Temperature in Paddy Soil under Long-Term Fertilization. Acta Pedologica Sinica, 2, 286-294.
Zhao, D., Liu, K., Ye, H., Hu, Z., Yu, X., Xu, X., Yang, X., Zhou, L., Hu, Q., Hu, H. and Huang, Q. (2018) Differences of Soil Nutrient Distribution in Profiles under Long-Term Fertilization in Upland Red Soil. Journal of Plant Nutrition and Fertilizers, 24, 633-640.
Zhao, J., Fan, X., He, H., Kong, L., Li, W. and Liang, T. (2019) Effect of Long-Term Fertilization on Available Nitrogen, Phosphorus and Potassium in Soil. Bulletin of Agricultural Science and Technology, 2, 116-118.
Fan, J., He, M. and Dang, T. (2000) Distribution and Accumulation of -N in soil Profile of Long-Term Located Fertilizer Experiment. Soil and Environmental Sciences, 9, 23-26.
Fan, J., He, M. and Dang, T. (2001) Effect of Long-Term Fertilization on Nutrient Distribution in Profiles of Black Loessial Soil. Journal of Plant Nutrition and Fertilizers, 7, 249-254.
Yu, H. and Zhang, E. (2014) Effects of Long-Term Fertilization on Soil Organic Nitrogen Fractions in Vegetable Soil. Liaoning Agricultural Sciences, 1, 13-16.
Xie, S., Yang, F., Feng, H., Yu, Z., Liu, C. and Wei, C. (2020) Organic Fertilizer Reduced Carbon and Nitrogen in Runoff and Buffered Soil Acidification in Tea Plantations: Evidence in Nutrient Contents and Isotope Fractionations. Science of the Total Environment, 15, Article ID: 143059. https://doi.org/10.1016/j.scitotenv.2020.143059
Nie, S., Huang, S., Zhang, S., Guo, D., Zhang, Q., Zhang, Y., Bao, D. and Chen, Y. (2012) Effects of Long-Term Fertilization on Soils: A Review. Soils, 44, 188-196.
Pernes-debuyser, A. and Tessier, D. (2004) Soil Physical Properties Affected by Long-Term Fertilization. European Journal of Soil Science, 55, 505-512. https://doi.org/10.1111/j.1365-2389.2004.00614.x
Menéndez, S., Lopez-Bellido, R.J., Benitez-Vega, J., González-Murua, C., López-Bellido, L. and Estavillo, J.M. (2008) Long-Term Effect of Tillage, Crop Rotation and N Fertilization to Wheat on Gaseous Emissions under Rainfed Mediterranean Conditions. European Journal of Agronomy, 28, 559-569. https://doi.org/10.1016/j.eja.2007.12.005
Ou, J. and Zhang, H. (2017) Study on the Effect of Long-Term Located Fertilization on Wheat Yield and Soil Fertility. Agricultural Science and Engineering in China, 29, 18-20+50.
Zhao, D., Wang, J. and Fu, X. (2016) Effect of Long-Term Fertilization on Soil Total Nitrogen and Its Fractions in Dryland Farming System. Journal of Soil and Water Conservation, 30, 303-307.
Zhao, P., Han, M., Xiong, Z. and Guo, T. (2018) Effects of Long-Term Fertilization on the Nitrification and Ammoxidation in Neutral Purple Soil. Soil and Fertilizer Sciences in China, No. 5, 85-90.
Zhang, Q., Zhang, X., Liang, B., Bi, M. and Li, J. (2017) Effects of Long-Term Fertilization on the Dynamics of Soil Enzyme Activity and Soil Nutrient under the Greenhouse Tomato-Cultivating System. Acta Agriculturae Boreali-Sinica, 32, 179-186.
Zhang, G. and Gong, Z. (2012) Laboratory Analysis Methods for Soil Investigation. Science Press, Beijing.
Li, J., Zhai, M., Huang, B., Liu, G., Zhao, Y., Sun, W. and Hu, W. (2017) Spatially Non-Stationary Relationships between Cation Exchange Capacity and Related Control Factors. Acta Pedologica Sinica, 54, 638-646.
Li, J., Xin, J., Zhang, H., Duan, J., Ren, Y., Sun, N. and Xu, M. (2015) Evolution Characteristics of Soil Nutrients in the Main Rice Production Regions, the Middle-Lower Reach of Yangtze River of China. Journal of Plant Nutrition and Fertilizers, 21, 92-103.
Gurlevik, N., Kelting, D.L. and Allen, H.L. (2004) Nitrogen Mineralization Following Vegetation Control and Fertilization in a 14-Year-Old Loblolly Pine Plantation. Soil Science Society of America Journal, 68, 272-281. https://doi.org/10.2136/sssaj2004.2720
Bhandari, A.L., Ladha, J.K., Pathak, H., Padre, A.T., Dawe, D. and Gupta, R.K. (2002) Yield and Soil Nutrient Changes in a Long-Term Rice-Wheat Rotation in India. Soil Science Society of America Journal, 66, 162-172. https://doi.org/10.2136/sssaj2002.1620a
Su, N., Yang, L., Zhou, C., Jie, X., Qu, H. and Gao, X. (2006) Effect of the Application of Organic and Nitrogen Fertilizer on the Content of Alkali-Hydrolysable N in Soil. Journal of Anhui Agricultural Sciences, 34, 6542-6543.
Xu, J. and Wang, H. (2001) The Nitrogen Fertilizer Utilization and Nitrogen Balance by Winter Wheat in Sandy Soil. Journal of Nuclear Agricultural Sciences, 6, 476-480.
Hu, R., Wu, J., Tang, S. and Luo, X. (2010) Effects of Long-Term Fertilization on Paddy Soils Organic Nitrogen, Microbial Biomass, and Microbial Functional Diversity. Chinese Journal of Applied Ecology, 6, 130-137.
Zhu, Y. (2016) Effect of Long-Term Fertilization on Soil Organic Nitrogen Composition and Its Relationship with Nitrogen Index. Shenyang Agricultural University, Shenyang.
Zhu, Z.L. (2008) Research on Soil Nitrogen in China. Acta Pedologica Sinica, 45, 778-783.
Malhi, S.S., Gill, K.S., Harapiak, J.T., Nyborg, M., Gregorich, E.G. and Monreal, C.M. (2003) Light Fraction Organic N, Ammonium, Nitrate and Total N in a Thin Black Chernozemic Soil under Brome Grass after 27 Annual Applications of Different N Rates. Nutrient Cycling in Agroecosystems, 65, 201-210. https://doi.org/10.1023/A:1022623405707
Zhang, X., An, J., Zhou, X. and Sui, S. (2012) Effect of Different Fertilization Modes on Maize Yield and Soil Nitrate-Nitrogen. Journal of Henan Agricultural Sciences, 41, 41-44.
Shi, J., Li, X., Wang, S., Li, S., Li, Y. and Tian, X. (2015) Effect of Long-Term Shallow Tillage and Straw Returning on Soil Potassium Content and Stratification Ratio in Winter Wheat/Summer Maize Rotation System in Guanzhong Plain, Northwest China. Chinese Journal of Applied Ecology, 26, 3322-3328.
Huang, T. (2014) The Mechanism of the Effect of Long-Term Carbon and Nitrogen Input on Soil Organic Carbon and Nitrogen Pool and Environment. China Agricultural University, Beijing.
Zhao, Y. Tong, Y. and Zhao, H. (2006) Effect of Different N Rates on Yield of Summer Maize, Fertilizer N Recovery and N Balance. Soil Fertilizer, 2, 30-33.
Zhang, J., Wang, C., Li, B., Liang, J., He, J., Xiang, H., Yin, B. and Luo, J. (2017) Effects of Controlled Release Blend Bulk Urea on Soil Nitrogen and Soil Enzyme Activity in Wheat and Rice Fields. Chinese Journal of Applied Ecology, 28, 1899-1908.
Li, W., Peng, B. and Yang, Q. (2015) Effects of Long-Term Fertilization on Organic Carbon and Nitrogen Accumulation and Activity in a Paddy Soil in Double Cropping Rice Area in Dongting Lake of China. Scientia Agricultura Sinica, 48, 488-500.
Bi, C., Chen, Z., Wang, J. and Zhou, D. (2013) Quantitative Assessment of Soil Health under Different Planting Patterns and Soil Types. Pedosphere, 23, 194-204. https://doi.org/10.1016/S1002-0160(13)60007-7
Luo, Y., Li, Z. and Liu, W. (2011) Effects of Long-Term Located Fertilization on Organic Matter, Nutrient and CEC in Upland Red Soil. Acta Agriculturae Jiangxi, 23, 133-136.
Wang, J. and Zhang, Y. (2011) Effects of Different Fertilization Systems on Soil CEC and Soil Acidity in Paddy Field. Chinese Journal of Soil Science, 42, 42-45.