Feed your crop according to what it is drinking: Water is the forgotten factor in crop nutrition.

 At this time of year the days are lengthening and increased sunlight means a greater potential for photosynthesis. The crops that are in the ground already are starting to make and store energy ready for the active growing period ahead. In a relatively short time, these plants will need to take in nutrients from the soil in greater and greater amounts to reach their genetic potentials for yield. All farmers are aware of this and are waiting for the ground to be fit to travel and for NVZ closed periods to come to an end so that they can start spreading fertilisers in spring.

It is January 2024 and much of UK’s farmland has received much more than its average rainfall over the past 12 months. As well as the physical damage caused through standing and running water, soils are now undergoing biological and chemical processes that will have long-term effects upon the nutrient status of soils and, a little further down the line, pollution of water courses, lakes and marine environments.

Crops drilled in autumn and winter will have had no shortage of soil moisture and, as a consequence, will not have had to put out much root to search for it. This could be a problem as the waters recede and, as seems more common, spring becomes droughty. This becomes even more problematic when nutrients, such as nitrogen, are leached away into groundwaters or are converted into nitrous oxides (due to the anaerobic conditions of waterlogging) which leave the soil to become greenhouse gasses with almost 300 times more impact than the same amount of carbon dioxide. Other, less mobile nutrients such as phosphates are physically removed from soils in that brown water run-off that you see on the roads next to fields.

This, then, is a “Triple-Whammy” of problems:

• Underdeveloped root systems for upcoming water deficits

• A depleted soil-nutrient status at the start of active crop growth

• Diffuse pollution of harmful substances to air and water

These are all problems that need solving for a crop to be productive & profitable and for the harm to the environment to be minimised.

It is often said that “it is hard to be Green when you are in the Red”, so the first thoughts going into spring might be: deal with the first two problems and hope that the third one sorts itself out. The crop is right in front of you and needs feeding; water courses and the upper reaches of the atmosphere are out of sight………… and out of mind. Initial thoughts might be to apply a decent amount of fertiliser as soon as possible to make sure that the rooting system picks it up rapidly. 

This, though, might actually compound problems even further.

Poor rooting means poor nutrient uptake efficiency so a large proportion of any applied fertiliser will be lost from the soil-root interface to do damage at a distance – the more you add, the more you lose. This is a waste of product & money to no benefit to the crop. Larger amounts of fertiliser will also have detrimental effects on the health of the soil, causing acidification and also slowing down the mineralisation of nitrogen from soil organic matter.

“Little and often” is a better approach to nurse crops through this stressful period, using small amounts of soil-applied fertiliser early on in conjunction with foliar fertilisers (applied as tank mixes with fungicides) once the canopy starts to show signs of growth. This makes best use of travel time, products and nutrient-use-efficiency whilst limiting environmental harm.

This approach will put the crop in a good position as it enters a period of rapid growth in spring and summer…….. where it will face problems caused by a lack of water.

The changing weather patterns are giving us milder, wetter winters but much warmer, driersprings and early summer. There are many ways to improve water infiltration and retention but, the reality is, soils will be short of water and therefore nutrient uptake could be limited. Throwing fertilisers at the soil in this situation is pointless as the prills or granules have no available water to dissolve them to make them available to plant roots – their only access point.

If any granular fertiliser should be in the soil after the wet period and going into the dry period, it will actually draw water to it, due to its high concentration of salt. As the soil continues to dry out, this solid fertiliser will, therefore, attract relatively more moisture making it even harder for the plant to take up water. In some cases it might actually draw water from the plant roots causing wilting and plant damage.

This is where foliar fertilisers can come into their own by providing readily available nutrients direct to target exactly when the plant needs it. 

There is some debate as to the usefulness of sap & tissue testing but it might be considered to give a snapshot of the nutrient status of a standing crop. Foliar fertilisers can address anytrace element deficiencies as well as feeding major nutrients such as nitrogen, phosphate, potassium and sulphur etc.

Nitrogen builds vegetation which is the “solar panel” providing sugars from photosynthesiswhich build yield. Phosphate is biology’s “power plant” and is responsible for energy flow throughout the plant, making sure that metabolism works. Sulphur is important for protein formation.

Potassium, though, is especially important in dry periods as it is the driver for water, and therefore nutrient, transport throughout the plant. Potassium forms highly soluble salts, so any potassium fertilisers applied in winter will have mostly disappeared throughout the period of high rainfall. A series of foliar applications of potassium through the spring will provide continued water transport and therefore keep the crop fed.

We are in a period of great change to the traditional weather patterns and, if we continue feeding our crops in the same way as we have done since the ubiquity of granular fertilisers, we will see poor economic returns on crops, more pressure on farmers and increasing harm to our air and waters. We have the technology, knowledge and products to mitigate many of the stresses of weather changes so now we need the mindset to use them.

For more information on how Agro-Vital and Agriton can help your farm adapt and still be kind to the environment, please get in touch.