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Independent.ie

Friday 9 December 2016

State of soil will be key to assessing viable crops

PJ Phelan

Published 01/02/2011 | 05:00

The past week has been spent surveying crop survival rates, telling guys not to rush into ploughing and finishing off the last of the soil sampling for soil organic matter. There is also some interest in starting to spread nitrogen on thin crops but this should be delayed until the middle to the end of next month.

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Winter wheat and barley have generally overwintered well, with little plant loss but less tillering and leaf area than normal. They are beginning to show the first signs of growth. Check soil results to find if you need to go in now with straight phosphate and/or potash fertilisers, or can you wait until nitrogen containing compound is justified?

Remember that if you apply nitrogen to saturated soils, or to soils that get rain and hold a lot of water after application, that the nitrogen will denitrify and become unavailable. Crops on land which are at soil phosphate (P) or potash (K) Index 1 or at the lower end of Index 2 will respond to an earlier P or K application. Check on soil minor nutrient status and note crops that will require trace element applications. Low lime status would aggravate problems. In all cases where nutrient levels are marginal, a firm seedbed is critical.

Many seedbeds have been disturbed by last month's frosts. If you find that plant anchorage is so poor that entire plants are removed by pushing the soil with the toe of your boot, then the seedbed needs to be consolidated by rolling. Delay rolling until soil conditions are suitable.

The reduced leaf area on crops, combined with seedbed disturbance, is putting pressure on soil residual herbicides and many crops will require spring herbicide application. Backward crops with even small overwintered weeds will be difficult to manage. Don't allow weeds to get ahead of crops and be particularly attentive to crops where rabbits or hares are grazing.

Damage

Oat crops in Tipperary have suffered considerable plant losses. Much of the damage has only become evident in the past two weeks. Plants have turned brown and crops look very bad from a distance. However, on closer inspection, some fields have sufficient plants to produce viable crops provided that no further damage takes place.

Crops with very poor and/or uneven plant stands will have to be 'taken out' and fields re-sown. Depending on the soil type, herbicide usage and/or weeds present, some fields will have to be ploughed. Others can be re-sown following shallow cultivations. The decision as to what is a viable plant stand will be determined by soil conditions and evenness of plant distribution.

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Last year I had a crop of Husky, with an uneven plant stand and averaging 40 plants/m2, which yielded slightly over 7.5t/ha (3t/ac) following the judicious use of a plant-growth regulator and the appropriate selection of fertiliser and its timely application. The extra costs of this were largely compensated by lower fungicide requirements.

Winter rape has taken a severe hit from pigeons but generally plant stands are good. Some late-sown crops appear to have survived very well, but time will tell. If ordering fertiliser, don't forget that sulphur should be included with the first nitrogen.

Soil conditions are satisfactory on some of the lighter soils. However, don't rush in until soil moisture below the plough layer is low enough to accept tractor/plough weight without resulting in soil compaction. Soil dries from the top down so, while surface conditions may appear good enough, you should assess the soil moisture underneath before ploughing.

You need to sample half of your fields that have been in continuous tillage for more than six-years for soil organic matter. If not, you are now liable for a penalty on your single farm payment.

Where soil organic matter is less than 3.4pc you must get a CC FAS adviser to recommend appropriate action.

A full list of CC FAS advisers is available on the Department of Agriculture's website, (www.agriculture.gov.ie)

PJ Phelan is an agricultural consultant based in Tipperary. Email: pj.phelan@itca.ie

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