Combination Crops on Organic Farms

Combination crops are becoming a very popular crop to grow on organic farms. The crop is a mixture of a legume - peas or beans & a cereal crop of barley, oats, wheat or triticale. Occasionally, the mix can contain two or more cereal species. Every effort must be made to source organic seed

Summary

• Combination crops typically contain 14 – 18% protein content making them a very efficient way of getting home-grown protein onto the farm
• They are a relatively easy crop to grow
• Legume - Peas or Beans fixes and supplies N for the crop
• Meet P+K requirement by using FYM, slurry or other suitable organic manure
• Combination crops can be harvested as wholecrop, crimped or taken to fully ripe

Orla Kinane, Digital Communications, Teagasc caught up with Martin Bourke, Organic Crops Specialist to discuss growing combination crops at the #OrganicBeef22 Open Day which took place on Wednesday, 28 October on the farm of John Purcell, Cashel, Co. Tipperary.

Sowing Date & Seeding Rate/Mixes:

The preferred sowing date for combination crops is late March/early April. It is important to be patient and allow soil temperatures to warm up sufficiently in Spring and for land to be adequately dry enough to ensure the crop emerges quickly and evenly. Aim to produce a fine, firm, level seedbed. Roll after sowing to keep moisture in the seedbed, especially in a dry season.

Sowing too early in Spring can lead to more bird attack. Crows in particular, like the legume component of the mix. Some farmers sow the legume separately to get the peas or beans down deeper to 2 inches. The cereal is sown with a second pass of the drill at about ¾ to 1 inch depth.  If using a pre-mix of both legume and cereal, aim for a sowing depth of about 1 inch.  Keep a watchful eye for bird damage in the early stages of establishment, and use appropriate deterrents such as scarecrows or bangers if required.

If peas are in the mix, ensure a ratio of cereals to peas at least 50%, but preferably 60% cereal and 40% peas. Peas on their own are prone to lodging, so the cereal acts as a support to prevent lodging.

N, P & K Requirement of Combination Crops  

As with any tillage crop, a recent soil test is the best starting point to address the nutrient requirement of a combination crop. The target pH for many tillage crops is slightly higher than for grass. Having the soil pH between 6.5 to 6.8 provides the best conditions to allow better availability of P and K for crop growth. The N requirement will be mainly met by the legume component of the mix being able to fix N for plant growth. Extra N and the P and K needs of the crop can be supplied with a suitable source of organic manure, such as FYM, cattle slurry or other organic approved manure source. Adjust rates of organic manure based on the P and K analysis from the soil test and the projected target yield of the crop.  It is very important to note the final yield of the combination crop. A high yielding crop will remove considerably more P and K from the soil than a low yielding crop. Ideally, the off-take of P and K should at least match the rate of P and K applied in the organic manure to grow the crop. 

Harvesting Combination Crops:

There are a number of ways to harvest combination crops, depending on which way the crop is going to be utilised.

Wholecrop

Cutting as a wholecrop and putting in the pit as fermented wholecrop involves cutting with a silage harvester fitted with a wholecrop or disc header. Alternatively, the wholecrop can be mown and then picked up with a grass header. Regardless of which silage harvester machine type used, the timing of cutting is important. The aim is to cut at a growth stage when the cereal in the mix is at the soft cheddar cheese stage. If harvesting too early, the crop will have a poor dry matter which increases the risk of poor fermentation and preservation. If left too late to harvest, the cereal grains may prove difficult for livestock to digest. The cereal straw and legume stems are a valuable source of effective fibre which is an essential component of a healthy rumen.

Crimp

Another way of harvesting combination crops is to harvest with a conventional combine when the cereal grain and legume grain are between 30-35% moisture. This is about 2 to 3 weeks before fully ripe and then crimp the grain. This involves passing the grain through a crimping machine which cracks the seed coat to expose the starch. The moist crimped grain is then ensiled in an airtight clamp.

Harvest Fully Ripe

The third option is to let the crop ripen fully and harvest with a combine. It is important to try and cut at low grain moisture, below 20% moisture. Closer to 15% moisture is preferable if planning to store the grain for longer-term use.

High moisture grain, if left in a pile, will heat quickly. Some growers store the grain in a loose shed and turn regularly with a loader to get moisture content down to 15%.  If the grain is a little higher in moisture at 7 to 25%, another option is to treat the grain with organic acid treatment - propionic acid.

More recently, it has become popular to roll grain at the time of organic acid treatment using a crimping machine. The grain is then stored aerobically in a vermin proof shed, and kept cool to prevent insect damage.

A forum took place at the OrganicBeef22 Open Day on the farm of John Purcell, Co. Tipperary on Wednesday, 28 September and was addressed by Minister Charlie McConalogue. The forum chaired by Damien O'Reilly included panel speakers Joe Bourke, Bord Bia; Catherine Roche, Irish Country Meats; Jack Nolan, Department of Agriculture, Food and the Marine; Pat Dillon, Teagasc and host farmer John Purcell

More information about the National Organic Beef Open Day

Contributed by Teagasc organic specialists - Martin Bourke, Joe Kelleher, and Elaine Leavy