Nitrogen is an important nutrient for crop growth. Soil nitrogen plays an important role in soil fertility. Even with large amounts of nitrogen fertilizer, 50% of the nitrogen accumulated in the crop comes from the soil. In some soils, The data in the data is higher. The total amount of nitrogen in the soil and various existing forms have a close relationship with crop growth. Analysis of soil total nitrogen and its various forms of nitrogen is the main basis for evaluating soil fertility and formulating reasonable application of nitrogen fertilizer. The soil nutrient rapid tester is an important instrument for measuring soil nutrients and is an essential monitoring instrument for the development of modern agriculture.
Most of the nitrogen in the soil exists in an organic state, and its content and distribution are closely related to the soil organic matter. Soil organic matter content is determined by the relative size of its annual formation and decomposition. The analysis results of soil nutrient rapid tester found that the nitrogen content in soil topsoil under various natural vegetation in China ranged from 0.044±0.027% to 0.503±0.200%. From the east to the west, the sequence of black soil-chernozem-chestnut-sandstone soil gradually decreased; from north to south, the sequence of black soil-dark brown soil-alkaline soil-brown soil-cinnamon soil decreased significantly. As a result, the nitrogen content of the yellow-brown soil continued to decrease toward the south; yellow-brown-red soil-brick and red soil gradually increased. In addition to being constrained by various natural factors, arable soil is also more strongly affected by artificial cultivation and fertilization. Its total nitrogen content is between 0.063±0.029% and 0.263±0.104%. The general soil is similar to natural vegetation soil. The highest black areas in the northeast China are the lowest in the Loess Plateau and the Huang-Huai-Huai Plain, the middle and lower reaches of the Yangtze River, the south of the Yangtze River, the Yunnan-Guizhou Plateau and Sichuan, and the southern, southern, Mongolian and Qinghai-Tibet regions. The latter has gradually increased according to the sequences of the middle and lower reaches of the Yangtze River, south of the Yangtze River, Mengxin, Yunnan-Guizhou Plateau and Sichuan, and south China, southern Jiangxi, Mongolian and Qinghai.
Through the soil nutrient rapid tester to measure different soils, it was found that different soils not only have different nitrogen contents in the topsoil, but also have different profiles. The humus layer of black soil is the deepest, which can reach 80-100cm or more, and the humus layer of chestnut soil is generally only 22-44cm. The profile of nitrogen also affects the nitrogen reserves of the profile. The black soil in the natural vegetation soil has the highest nitrogen content in the surface layer and the deepest humus layer, with the highest nitrogen reserves, followed by dark brown soil, brick red soil, red soil, chernozem, chestnut-calcium soil, and ash-calcite soil. Brown desert soil has the lowest nitrogen reserves. In the arable land, except for the northeast black soil area, the soil N in the Taihu Lake area has the highest reserves, and the Huanghuaihai Plain and the Loess Plateau are the lowest.
Most of the nitrogen in the soil exists in an organic state, and its content and distribution are closely related to the soil organic matter. Soil organic matter content is determined by the relative size of its annual formation and decomposition. The analysis results of soil nutrient rapid tester found that the nitrogen content in soil topsoil under various natural vegetation in China ranged from 0.044±0.027% to 0.503±0.200%. From the east to the west, the sequence of black soil-chernozem-chestnut-sandstone soil gradually decreased; from north to south, the sequence of black soil-dark brown soil-alkaline soil-brown soil-cinnamon soil decreased significantly. As a result, the nitrogen content of the yellow-brown soil continued to decrease toward the south; yellow-brown-red soil-brick and red soil gradually increased. In addition to being constrained by various natural factors, arable soil is also more strongly affected by artificial cultivation and fertilization. Its total nitrogen content is between 0.063±0.029% and 0.263±0.104%. The general soil is similar to natural vegetation soil. The highest black areas in the northeast China are the lowest in the Loess Plateau and the Huang-Huai-Huai Plain, the middle and lower reaches of the Yangtze River, the south of the Yangtze River, the Yunnan-Guizhou Plateau and Sichuan, and the southern, southern, Mongolian and Qinghai-Tibet regions. The latter has gradually increased according to the sequences of the middle and lower reaches of the Yangtze River, south of the Yangtze River, Mengxin, Yunnan-Guizhou Plateau and Sichuan, and south China, southern Jiangxi, Mongolian and Qinghai.
Through the soil nutrient rapid tester to measure different soils, it was found that different soils not only have different nitrogen contents in the topsoil, but also have different profiles. The humus layer of black soil is the deepest, which can reach 80-100cm or more, and the humus layer of chestnut soil is generally only 22-44cm. The profile of nitrogen also affects the nitrogen reserves of the profile. The black soil in the natural vegetation soil has the highest nitrogen content in the surface layer and the deepest humus layer, with the highest nitrogen reserves, followed by dark brown soil, brick red soil, red soil, chernozem, chestnut-calcium soil, and ash-calcite soil. Brown desert soil has the lowest nitrogen reserves. In the arable land, except for the northeast black soil area, the soil N in the Taihu Lake area has the highest reserves, and the Huanghuaihai Plain and the Loess Plateau are the lowest.
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