The construction of the evaluation index system is an important part of the soil testing and fertilizer application system. It is the main method for screening and verification of soil nutrient testing methods and establishment of a recommended fertilization index system suitable for local conditions. It is developed in accordance with the “3414†plan, and the soil testing formula The application of fertilizers is extensive. However, the time and period of sampling should be taken into account when using it for soil fertility experiments:
1. Sampling time Collected after the crop is harvested or before sowing and fertilizing, generally after the autumn. Facilities vegetables are collected during the hanging period. The orchards are collected before the first fertilization after fruit picking, and saplings and unfruiting orchards should be collected before the expansion of the hole in the clear garden. When nitrogen fertilization is recommended, it should be collected before topdressing or during the critical period of crop growth.
2. Sampling period The same sampling unit, inorganic nitrogen and rapid diagnosis of plant nitrogen nutrition collected once every quarter or every year; soil available phosphorus, available potassium and other generally 2 to 3 years collected once; medium and trace elements generally 3 to 5 years collection 1 time.
1. Sampling time Collected after the crop is harvested or before sowing and fertilizing, generally after the autumn. Facilities vegetables are collected during the hanging period. The orchards are collected before the first fertilization after fruit picking, and saplings and unfruiting orchards should be collected before the expansion of the hole in the clear garden. When nitrogen fertilization is recommended, it should be collected before topdressing or during the critical period of crop growth.
2. Sampling period The same sampling unit, inorganic nitrogen and rapid diagnosis of plant nitrogen nutrition collected once every quarter or every year; soil available phosphorus, available potassium and other generally 2 to 3 years collected once; medium and trace elements generally 3 to 5 years collection 1 time.
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