Soil Nutrient Requirements To produce a good crop, maize plants need to grow very rapidly once they have germinated. They will do this providing the soil moisture and structure are good; the temperature is warm, and nutrition is adequate. Maize can easily produce 50 t/ha of fresh weight in a period of four months. To support this rapid growth, it has a large demand for nutrients and any shortage will restrict early growth and final yield. Although established crops have a well-developed root system, root growth is slow in the early days of the crop, especially if the weather is cold. Poor root growth means decreased uptake of nutrients and this can be a vicious circle as poor uptake of N and P can restrict root growth. For this reason, it is advised that a starter fertiliser is placed close to the seed, even when the bulk of the soil is adequately supplied with nutrients. If you are looking at fields that traditionally suffer from run-off or are prone to erosion, then consider a slightly earlier maize variety (modern genetics often mean that you won’t lose yield and often gain some quality) and look to place a cover crop in to help scavenge nutrients and stabilise surface soils. This in turn can be used as a green manure, used for grazing or potentially harvested before the following crop. Maize is a very convenient crop on which to apply manure in the spring when there are limited opportunities for spreading on grassland. Be careful that applications do not exceed 250 kg/ha of total nitrogen to conform to the Code of Good Agricultural Practice and NVZ requirements. Index: SNS 1, 2P & 2K Low Yield 9t DM/ha High Yield 15t DM/ha Field Yield 30t/ha (12t/ac) 50t/ha (20t/ac) Nitrogen 100kg/ha 150kg/ha Phosphorus 45kg/ha 65kg/ha Potash 130kg/ha 220kg/ha As maize is a valuable crop with a high demand for nutrients it is important to know the soil pH and available nutrient levels in order to apply the necessary lime and fertiliser to ensure good crops. When the maize field has been chosen a soil sample should be taken for analysis unless the field has been tested within the last 3-5 years. Bartholomew’s provide a complete soil analysis package which allows a tailored approach to nutrient management. 19 Maize Handbook 2020
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