Intercropping grain peas with barley (DiverIMPACTS Practice abstract)

Benefits The barley provides support to the peas, preventing lodging and, thus, reduces yield loss. It increases the soil cover and thus suppresses weeds. Growing two crops at the same time also mitigates the risk of yield loss in one of the crops. With intercropping there is a higher land utilisation per hectare than with pure stand. Practical recommendation • Finding the suitable varieties to combine (same maturity) can be accomplished by a simple strip trial. We use half-leaved peas varieties. • The seedbed should not be too fine-grained after cultivation or reduced tillage (advantage: better channel flow from deeper soil layers during drought periods). A further possibility is mulch-till, whilst on heavy soils a plough might be needed. Possible application of green manure or compost. • For sowing machines with only a single tank, homogeneously mix the seeds at a seed rate of 80% of pure pea stand density and 40% of pure barley stand density before filling the seeder. During sowing, repeatedly check the homo-geneity of the mixture, and for sowing machines with two or more tanks, apply the seeds of the mixture species separately. The mixing ratio might be adapted over time according to local growing conditions. • To avoid yield loss due to drought during the blooming stage, it might be better to sow the mixture in autumn. The blooming stage is then earlier, at a time when more water is likely to be available. However, spring sowing is also possible. • Sow with a cereal drill at a row spacing of 12 cm and a placement depth of 3 to 4 cm into the same or in separate rows (depending on the sowing machine). Do not sow too early to keep the pea plants small enough during winter. • Weed control is usually not needed, but a high weed pressure can be controlled by harrowing in early stages. • No nitrogen fertilization for the crop is needed. Irrigation would only be needed in extremely dry year. • Harvest: adjust harvester sieves to peas. Open threshing concave and hulling bars wide enough. Low drum rotation. Keep the airflow lower compared to a pure pea harvest; check regularly for grain loss. Place the vario-table in the back. Adjust to an aggressive cutting angle. • In order to avoid legume fatigue in the soil, only cultivate the mixed crop every seventh year. Do not grow lupines, vetches, lucerne or pure stands of red clover in between. In case of Legumes fatigue do not cultivate peas for 10 years. • To market the harvest, equipment to separate the two components might be needed. Talk to your local collection station. If more farmers use the intercropping system, they might see the advantages. Practical testing If this method seems to be suitable for your farm, we recommend that you test it under your own farm conditions as follows: 1. Before sowing, separate a narrow plot from the field that is large enough for two harvester widths. 2. Mark the plot of the trial area with two poles. 3. Apply the new method on the narrow plot. The rest of the field can be cultivated as usual (e.g. peas in pure cultivation).