Farm Ireland

Sunday 18 March 2018

Opt for lime to boost crop growth

Gerry Bird

The past week has been busy on the land, with good drying conditions facilitating fertiliser and herbicide application on winter crops. Oilseed rape crops vary from nearly non-existent to full ground cover depending on the level of pigeon activity.

Fertiliser applied should contain boron and sulphur as rape responds well to these nutrients, especially on loamy soils. Residual herbicide application should have been completed by last month, and good activity is evident in treated fields.

The first fertiliser splits are being applied to winter crops. The quality of seedbeds is evident, with the majority of crops a good green colour before fertiliser application.

Crops which had been rolled in less-than-ideal conditions have browned off and are under stress, with leaf die back. Poor patches are evident, relating to variable soil type in the field, which have become compacted due to the initial damage at drilling and compounded by recent weather conditions.

Damaged headlands and weak patches in fields tend to deteriorate further with a drop in pH and subsequent poor fertiliser usage.

Growers have finally got the opportunity to roll winter oat crops, and this should help to stabilise the root systems and get the crop growing again with the help of applied fertiliser.

Reduced rates of phosphorous have been a common practice over the past few seasons, due mainly to the price of fertiliser and grain. Despite the current fertiliser prices, many growers realise that yields suffered last year due, at least partly, to low soil phosphorous levels. As a result, compounds with good phosphorous content are popular.

I have noticed quite a bit of lime being spread over the past few weeks particularly on grass, but also on ploughed stubbles. Lime is an essential component for good crop growth and the optimal usage of fertiliser.

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Nitrogen availability is reduced at low pH values. So if you apply 54units/ac (67kg/ha) of nitrogen at pH 5.5, it will probably only result in 41 units/ac (51kg/ha) of plant uptake, with only a third to a half of the phosphorous taken up. Lime contains calcium, which is an important nutrient in its own right, and, in addition to neutralising the soil, it is vital for major plant functions.

A winter wheat crop could have received nearly a tonne of pure nitrogen in the previous five seasons, but may never have received lime.

On the question of fertiliser, growers should remember that records of nitrogen and phosphorous applied last year should be in place by the March 31 deadline in order to be Nitrates compliant.

Sprayers are in full flight around the country applying herbicide to winter cereals. Grass weeds are between the three-leaf stage to early tillering, with the hardy broadleaves such as speedwell, chickweed and cleavers to the fore in many fields.

Combinations of DFF at 0.25l/ha and IPU at 2-3l/ha are still being applied to winter wheat, and are quite effective when weeds are small. However, well-tillered grass and advanced cleavers will require more robust treatment later in the season. The activity of herbicide is temperature sensitive, so if you are spraying in the next couple of weeks, check that the product will work at low temperatures. The sulphonylurea and hormone herbicides work best when the temperatures are conducive to plant growth.

Several growers have drilled beans in excellent conditions and, with good contracted prices, crop potential looks good. Beans are a relatively easy crop to grow and are an excellent break crop, improving soil condition and fertility.

In the northeast and midlands, the first crops of spring barley have been drilled on the lighter soils in good conditions.

Experience has shown that on some of the heavier soils, early drilling can present problems when seedbeds are partially dry. In particular, germination and establishment can be variable if rain follows drilling. Significant rainfall shortly after drilling can saturate the soil around the seed, squeeze out the air and, if the soil is over tilled or too firm, the wet conditions persist and germination is affected.

It is great to be heading into the season with a good sense of optimism. Let's hope it's all justified.

Gerry Bird is a crop consultant and member of the ITCA. Email:

Indo Farming