Check your swards and soils now
Two important tasks which should be carried out over the next month are soil analysis and grass sward assessment.
Regular soil analysis is required under phosphate regulations and this should be carried out every four years across the farm. A simple plan should be to test a quarter of the farm each year. One soil sample per field (made up of 25 sub samples) up to 10 acres is sufficient. If the field is larger a second sample is required. Where problem areas within a field have been identified in the previous years these areas should be sampled on their own. It is not uncommon to have areas within fields which show lower pH or nutrient status figures. This in turn can reduce the production of the sward or crop.
Determining the soil levels for P and K means that fertiliser levels can be adjusted to meet individual field requirements. This means that money can be saved on fertiliser application or crop yields maintained at a higher level. The optimum soil phosphorus level for arable crops, intensive grassland and silage is an index 2. The optimum soil potash level is 2- but always check RB209 or the nutrient calculator on the DAERA website as additional applications will be required particularly for arable crops.
Ph, the other main figure from your soil analysis and perhaps the one to which least attention is paid. Aim should be 6.2 for grass minimum and 6.5 for arable crops to improve the efficiency of fertiliser and slurry that is applied. At a pH of 6 89% of nitrogen is available, 52% of phosphate and 100% of potash. As an approximate guide 1 kilo of CACO3 is required to counteract each kg of nitrogen applied (varies with type of nitrogen) or 12kgs of CACO3 for every 1000gallons of slurry. The best advice is to bring your pH up to the correct level and then apply Granucal each year to maintain ph at the optimum level.
Plan to walk swards over the next month and check which need attention come the spring. Check the level of perennial ryegrass in the sward. As a general guide perennial ryegrasses have a red colouration at the base of the stem and a shiny underside of the leaf, weed grasses do not. The minimum you would require is that 50% of your sward is made of ryegrass. This should give 75% ground cover. If groundcover is less this allows weed grasses to invade which reduces sward yields and slows regrowth. Modern grasses response to nitrogen will be five times higher than in weed grasses.
A maximum of 10% for broad leaved weeds to include docks, chickweed, thistles and creeping buttercup. A four year study at IGER North Wyke found that where docks covered 20% of the field area, a control programme saw the treated plots yield 3.4t/ha more/year on average. A single dock plant can produce up to 60,000 seeds per year which can remain viable for 80 years. It may be that the sward has reached a level of weeds where it is not economic to control them and only a full reseed will help sort the problem.
Many fields have suffered damage because of the high rainfall over these past few months, especially those which have been cut for silage. The worst fields should be ear marked for remedial action in the spring by overseeding or for a complete reseed by undersowing a cereal crop which could be cut for silage so as not to lose any production.
If possible take a spade out and dig to a depth of 40cms to check for soil compaction. Signs include rusty grey mottled colour, foul smell, poor root penetration (should be 30cms), lack of earthworms (normally 10-15 in each spade) and no vertical cracks. Plan to tackle these problems in the spring if weather allows. For shallow compaction up to 10cms use a soil aerator with knives or spikes. For compaction at 10-15cms use a sub-soiler or sward lifter.