Don’t let a dry April slow crop growth. Soil nutrition matters more than ever

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There is a saying that many farmers will be familiar with: wet soils make crops lazy. As you would expect, this is not a scientific fact, but there is some truth to it. Following record levels of rainfall over winter, we have recently been confronted with an especially dry March and April. Soil moisture is suddenly a huge problem for many farmers dealing with their spring crops. How is this possible so soon after a prolonged period of wet weather?

The truth is that heavy rainfall causes shallow root systems. Deep roots die in anaerobic conditions. As an industry, the weather often catches us by surprise. However, if you look at the data, current conditions are actually in line with expectations – it’s merely our attitude that might require shifting.

We have a common misconception that April is a fairly wet month with consistent rainfall, and drought would be a rarity. The data, however, does not correspond with this theory. Looking at past weather patterns, April has been 28% drier in recent years compared to figures pre 2000. This trend continues even further. Over the last 100 years, April and March are often the driest months in the year. These dry conditions surprise us every time, but the data indicates that it is a problem we can anticipate and overcome.

What we can take from this is just how critical moisture retention is, even after a wet winter. The focus always has to be on strong soils and root systems. In recent years, particularly since the turn of the century, our N recommendations have taken this into account. We have promoted higher application rates at an earlier time in order to build up crop canopies, resulting in larger root systems below the ground.

We’re now faced with the threat of drought, the severity of which will determine how much crops suffer. To an extent, we have to take some of it on the chin. If, after getting out with a spade and checking your situation, there is enough moisture to keep your crop going, it’s a good idea to investigate foliar nutrition products. A robust plan that uses micronutrients and all the right products in your armoury can keep crops going until rainfall arrives.

Looking at nutrition – where do we go from here?

Strategic use of the right products can bring us through this difficult period. Micronutrients need micro amounts. Foliar products can generally be used throughout the whole crop. For macronutrients, particularly nitrogen and potassium, large amounts will be required via the soil.

In terms of nitrogen for spring barley for example, we at Yara have run tests across a wide range of application rates to find the sweet spot – from 0kg/ha up to an excessive 240kg/ha. We have mapped and correlated to determine that yield results are the strongest return on investment at 161kg/ha. That might seem ridiculously specific – and you certainly can’t guarantee reaching that number precisely – but it’s a good target to aim for. In our wheat trials, looking back at the dry spring of 2017, the optimum N rate then was 215 kg N/ha. There was also some evidence in that year that keeping 40 kg N/ha for a GS39 application was beneficial.

The weather may catch us off-guard but the data – and tools to move forward – are at your disposal. Don’t overlook them. In the short-term, start thinking about how you can keep your crop moving along. In the long-term, seek out useful data or those with knowledge in that area. There is no reason we should be unprepared.

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