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Using GPS positioning technology, site sampling was conducted for grain fields in Yutian County, Hebei Province. Select 1 or 2 representative plots from each village of 38 villages in Hongqiao Town, Yutian County; select 3}7 representative villages from each township (town) of 19 other townships (towns) other than Hongqiao Town , Select one representative plot in each village. The sampling point is set near the center of a representative plot, and its distribution is shown in Figure 1. The sampling depth is 0}20an, and the soil nutrient content of the sample is measured using a soil nutrient speed meter.
On the basis of soil nutrient comprehensive system evaluation method and crop high-yield and high-efficiency balanced fertilization technology, the results were based on [no.m. The core of the technology is the use of combined extractants and serialized operating procedures to quickly and accurately determine and fully evaluate the status and supply capacity of various macro-, micro-, and micronutrients in soils, and to ensure that all kinds of nutrients are achieved on this basis. Balanced supply of balanced fertilization technology system.
Through the determination of soil nutrient fastness tester, we found that the soil nutrient available content analysis applied soil nutrient status system research method [Zu]. Combined extraction and determination of P, K, Cu, Fe, Mn, and Zn: Extractor AS AS solution (0.25m plant LNaHC0, 3-0. Olmo plant LEDTA 0. Olmo plant LNH4F); P platinum crucible Anti-colorimetric method, K, Cu, Fe, Mn, Zn were measured by atomic absorption spectrophotometer. The combined extraction and determination of NH-N, Ca, and Mg: the extracting agent was a 1mol/L KCl solution; the NH-N-N was determined by an indene blue colorimetric method, and Ca and Mg were determined by an atomic absorption spectrophotometer. Extraction and determination of S: extractant 0.08mo1/LCa (HzP04): solution, determined by BaC1 nephelometry. Organic matter (OM): The extractant was 0.2 mol/L NaOH-0.1Ol mo LEDTA-2% methanol, colorimetric determination. PH: The ratio of water to soil is 2.501, measured by a composite electrode.
P applied to calcareous soil in the north can be converted into octacalcium phosphate or deca-calcium phosphate, and the higher the content of clay and powder in the soil, the stronger the soil's ability to fix phosphorus, and the P applied to the soil is converted to phosphoric acid. The greater the possibility of octacalcium or calcium phosphate phosphate, the soil available P measured by the soil nutrient speed meter showed a tendency to decrease with the increase of clay and powder particles.
The Huang-Huai-Hai Plain is the main type of agricultural natural economy. The area of ​​cultivated land is 7291 ang, of which wheat, corn and rice are 286, 432 and 161 n2 respectively. The main landforms are alluvial and alluvial plains. The topography is high in the northeast, the central plains, and the southwest canopy. The main areas are fluvo-aquic soil and cinnamon soil. The average annual precipitation in this area is 693.lmm, the average annual temperature is 11.2e, and the frost-free period is around 19oa. The main production of wheat, corn, rice, vegetables, apples, grapes and so on.