For the Future of Farming

Nutrient Management for the Maize Crop

Afbeelding: maize web

Modern maize varieties grown in well structured soils with adequate nutrition will regularly yield 40t/ha fresh yield and often in excess of 50t/ha fresh weight. From drilling to harvest this will happen in around a four month period and to support this rapid growth the demand on the soil to supply the required nutrients is huge and any deficiency will restrict early crop development and ultimately yield and quality.

Apart from a minimal amount of foliar applied fertilisers in certain circumstances all the required nutrients must be supplied by the soil and taken in by the plants root system. Therefore the grower must do all he can to ensure that the needs of the crop are met with a correct and balanced nutrient supply.

The Average Maize Crop

As we have already mentioned, maize crops grow a large amount of fresh material in a short time and to deliver these yields requires all the key nutrients to be in place at the right time and in sufficient amounts.

The average 40t/ha maize crop will remove:

  • 160kg/ha of Nitrogen (N) (peak requirement 210kg). The key driver of yield and quality, and involved with photosynthesis, leaf and stem growth. Excess will delay maturity and starch quality. Deficiency will reduce dry matter yield and starch content.
  • 55kg/ha of Phosphorus (P) required by the growing points of most plants but especially maize and critical for root development particularly in the early growth stages. Cold weather at planting and poor soil structure are also very influential on the availability of Phosphorus from the soil’s reserves.
  • 175kg/ha Potassium (K) with a peak demand of 360kg/ha. Perhaps the most influential and most overlooked nutrient for the maize crop. At peak, the crop will demand and contain more K than N. A major factor in yield, without an unhindered supply of K yield will always be compromised. K is involved in the transport of sugars from the leaves to the cobs where it is turned into starch. Poor or incomplete grain fill is a classic sign of insufficient K.
  • 40kg/ha Magnesium. (Mg) A key component of chlorophyll and therefore photosynthesis. Excess Mg can limit uptake of K so important not to oversupply. Background soil Mg requires careful monitoring.
  • Various micro-nutrients notably Zinc and Boron which although not required in large amounts, have a significant role to play in the development of a healthy maize plant and in particular cob and grain development and therefore starch content of the crop. Modern maize varieties will consistently yield 50t/ha and consequently nutrient requirements will be considerably higher and any shortfalls will be much more obvious.

Soil pH

Perhaps the most significant influence on nutrient availability is the soil pH. Most nutrients that play a significant role in maize are at their most available between pH 6.0 and 7.0 (depending slightly on soil type) with pH 6.5 being an accepted target to cover most bases. It is key therefore to regularly soil test to ensure that the soil pH and the status of the critical nutrients is known. Determining which nutrients are in excess is as important as knowing which are in deficit. With a regular soil testing regime and taking into account any organic manures applied (which it is also prudent to analyse, as many growers consistently over estimate their value and the amounts they apply) it is then possible to create and implement a cost effective nutrient management plan tailored to each field and matching crop expectations.

For the 2018 maize season to assist our customers in planning their 2018 maize crop, ForFarmers have launched a dedicated maize soil test. The ForFarmers Maize Extra soil test analyses all the essential parameters in one convenient test.

For more information on ForFarmers Analytical Services, including soil testing and Nutrient Management Planning or to speak to one of our FACTS qualified advisors please call 0845 070 6280.