Combining Peas are a valuable break crop not only producing a high protein grain but also leaving residual nitrogen in the soil for any following crop.
The first step when planning a pea crop is to decide what market you are growing for. Many types of peas are suitable for a range of premium markets but all types are suitable for animal feed.
Current varieties of marrowfat peas for human consumption are relatively lower yielding than other combining types and are more expensive to produce, the flip side to that is that they can command a high premium.
By far the biggest type of combining peas grown are the white flowering types which are suitable for all types of markets. These are broken down into further classifications of white (yellow), large blue, small blue and marrowfat. White Peas are used mainly animal feed whereas large blues can be used for micronizing, small blues can be used for canning and marrowfats are mainly for human consumption with a large proportion being exported.
Sowing and establishment
The actual kilos per hectare sown should be governed by the Thousand Grain weight of the seed (TGW).
Target plant populations should be set according to the type of pea being sown. Marrowfats should be around 65-70 plants per m2, and most of the other classifications should be at around 70 plants per m2. The variety “Zero 4” should be set at a higher population of 110 plants per m2. These populations are the average recommended by the Processors and Growers Research Organisation (PGRO) as the most profitable level for each type. – targets can be lower on more fertile soils whereas higher populations may be beneficial on light, drought prone soils or where there is a risk of attack by birds.
Field losses and germination should be taken into account when working out the seeds sown per square metre with field losses of between 5% for April sowings up to 15% for February sowing being allowed for.
It is recommended that a rotation should carry no more than one crop in 5 of either Peas, Field Beans, Green Beans, vetches or Lupins. This 4 year break between any of these crop groups is the minimum recommended without the increased risk of building up persistent, soil borne pests and diseases in the field.
Peas are a spring sown crop. On medium to heavier soils, autumn ploughing often takes place to allow the natural weathering of the soil to take place which will aid the production of an adequate tilth in the spring with minimum further cultivation. On lighter soils, spring ploughing is an option where overwintering stubbles is required. Peas are sensitive to compaction.
The benefits of early drilling can include a higher yield, earlier maturity and some escape from pests. It is however important to drill peas when the soil is drier and less prone to compaction.
Most cereal drills are suitable for drilling peas. The drill should be accurately calibrated for each seed lot before sowing, taking into account TGW, germination and drilling time (potential field losses). Drilling should be in rows of 20cm or less. Narrower rows result in higher yields and tend to give more even crops with better weed suppression and easier combining. The seeds should be sown so that they are covered by at least 3cm of settled soil after rolling. An adequate plant population is essential since low populations are more difficult to harvest, later maturing and more prone to bird damage.
On most soils it is a necessity to roll the field to depress stones in order to avoid damage to the combine. Rolling should be done soon after sowing and well before emergence.
Fertiliser requirements for peas are small with no N being required. Where P & K are required it should be put deep enough into the seedbed to allow full utilisation by the crop. Peas may suffer from Sulphur deficiency on poor light textured soils and where this deficiency is suspected and application of 25-35 kilos per hectare as a pre-drilling treatment is suggested.
Care must be taken in harvesting peas as a premium is often available for high quality produce. Quality can be affected by wet weather at harvest, causing stating in a lodged crop and if destined for the human consumption market, value is reduced if pea seed becomes bleached.
If peas are left in the field for too long until the moisture content is 12% (also if they are overdried after harvest), the crop may not be suitable for human consumption as the percentage of “non soakers” increase and the seed may also split and crack. Yield can also be lost of the peas are left in the field for too long as shelling out and pod shattering can occur therefore harvesting at the right time is essential.
Harvesting at 18% moisture of peas for human consumption can avoid bleaching, shelling out losses and splitting or the deterioration in quality. For animal feed, harvesting later at 16% moisture will reduce drying costs. Although these should be free from moulds, split or stained peas do not adversely affect the value of the crop.
Yield & Nutrition
The expected yield of combining peas are 4 – 4.5 tonnes per hectare from a Marrowfat Pea and 4.5 – 5.0 tonnes per hectare for White and Large Blue varieties with the makeup of the grain consisting of:-