Intercropping in arable farming

Findings include:

• An oat companion crop significantly increased linseed yield
  
  
• Intercropping wheat with beans resulted in much lower weed biomass compared to the monocrop - 73% and 74% weed reduction in 2018 and 2019 respectively
  
  
• The pea crop may have facilitated nutrient supply for oilseed rape when no artificial nitrogen was being applied. The peas provided insurance when the oilseed rape failed to make it to harvest
  
  
• Linseed with oats was the only combination in which statistically significant yield differences were detected, but this may be due to a higher number of replicates and a higher sampling effort. More sampling at the other plots would increase the strength of the results

In 2019 three trials are being established on two farms. The two field lab farmers have developed plant team trials to test a certain objective of their choice.
T1: Test the effectiveness of oats in reducing linseed loss during establishment via reduction of pest and disease pressure.
T2 (A): Test the effectiveness of oats in reducing spring oil seed rape (SOSR) losses (in a crop which is also intercropped with peas) via reduction in pest and disease pressure.
T2 (B): Test the effectiveness of SOSR in supporting the pea crop and reducing lodging.
T3: Test whether intercropping beans with wheat reduces the weed burden in the bean crop and increases the protein content in wheat.

Plant teams will be drilled in winter/spring and harvested in summer 2019. Each trial has different data collection priorities to address the objective, as determined by the farmers, but yield will be collected from all field-scale strips by farmers using their combine monitors and separating a subsample to determine crop ratios. Quadrat sampling will be primarily undertaken by the farmers with support from ORC/LEAF researchers. Farmers will collect data such as crop establishment and yield data, whilst weed burden, pest and disease pressure and degree of lodging will be analysed by the researchers.

We are definitely doing this again next year, we’d be stupid not to! In fact, we’ve already ordered our seed.”

“The beans were our main crop so any wheat we got was a bonus. We actually saw slightly lower bean yields where we intercropped but this was more than made up for by the wheat. Crucially, we saw 64% less weed biomass in the intercropped plots. With far fewer weeds, we should have a much cleaner field next year."

“This is our first foray into intercropping and we are convinced it was worthwhile. Having the extra biomass in the form of a wheat crop - rather than weeds - is hugely beneficial. Next year, we’ll probably drop the wheat rate to around a third to try and boost our bean yield while still suppressing the weeds.”

• Beans and wheat with 2 bean varieties used (Vertigo and Fanfare)
• Poor establishment of the beans in the intercrop and monocrop plots.
• Fanfare performed slightly better than Vertigo but not significantly different.
• Drilled late and seed only had 65% establishment so would have effected how successful the beans establishment combined with this years weather.

Conclusions

• Adjust seed weight in the intercrops (increase)
• Adjust timings (Try to drill earlier)
• Adjust variety (a winter bean variety may be more successful- Tundra?)

• Rain rotted some of crop (Mono and Inter) then had no rain meaning spring crops were awful this year.
• Spring OSR very low due to slug damage, wetness, anything that did grow was eaten
• Didn’t harvest any rape in trial, in another trial with sandy soil some Rape was harvested.
• Big issue will Pollen Beetle which wouldn’t leave the S.OSR alone.
• Next year, wouldn’t manage or spend any money on the OSR, just let it grow as it is.
• In previous years with Peas and Rape intercrop no dry fertiliser was used but there was no nutrient deficiency.
• Wasn’t any marked difference in beans in the mono and Inter plots. No N deficiency despite low N application.
• Beans at Inter 245 kg/h rate out yielded the 345 Kg/ha
• Mono from the Quadrat samples but didn’t on the combine.
• Foot rot present which will have effected yield on combine.
• Less yield in the intercrops due to no OSR
• Intercrops had more flowering of beans but the heat aborted any extra pods
• Slightly more weeds in the intercrop (due to no OSR)
• Beans were a bit further back compared to OSR in terms of moisture but there was not enough OSR for it to cause an issue. This could be due to a lower density of beans in intercrops.
  
  Harvest
• Not enough OSR to know how the combine would go through the intercrop
• Had a gross margin loss in the intercrop (Money used trying to keep pollen beetle back).
  

Pests

• Reading trialled Mustard around crop to treat Flea beetle, which reduced prevalence on OSR. Beetle still prefers the OSR vs the mustard
• Can’t do this on a field scale, could use mustard instead of OSR in the intercrop, but may struggle to destroy the mustard
• There is experience in spraying for Pollen beetle before which removed the pollen beetle but the next day high prevalence of Pollen beetle was high again.
  
  Linseed, lentils intercrop
• Lentils worked well, Linseed thinned out more than would normally.

• Used Wheat (which they already had) and Tundra Beans
  
• They are convinced it was worthwhile and will do it again this year
  
• Drilled in October (2 passes on the same day)
• Ideally would use 50%:50% mix for yield but it is not best for weed suppression. This year used 25% beans and feel could do 30% beans and still get the weed suppression needed. It is a lot of wheat but no negative yield hit as being using for feed.

Establishment

• Slightly lower than normal, which was due to it being very wet and then very dry (also caused large cracks within the soil)

Weed suppression

• Has a big wild Oat problem and visually the intercrop had less wild oats present
  
• Hoping the Seed return from wild oats will be lower in the intercrop plots this year (theory would be ½ than normal)
  
• 63% reduction in wild oat biomass in Intercrop vs Monocrop
• 1.9 t/ha for the intercrop, which is a slight yield hit on the beans but had a lot of wheat so together no yield hit.

Protein analysis

• No protein analysis done but could be as there are still samples of the Inter and Monocrop.

Harvest

• Did have to wait a little for the beans to ripen but no wheat dropped out. Not sure what would happen with more rain
  
• Worry of intercrops would be 2 different harvest dates Isn’t a problem for us as a slight loss in wheat isn’t a issue due to it being used as fodder.
• Intercrop was a growth stage or 2 ahead of the monocrop, flowering was at least 2 days before monocrop.

Conclusions

• Will try to drop the wheat rate to 1/3 of normal rate and increase beans
• Overall happy with the intercrop, especially useful biomass vs weeds

• Grows Carlin Peas for Hodmedod's. Traditional UK pea.
• Previously struggled with Lodging so trials Peas, Triticale to help with this and for livestock Fodder
• 10% Triticale plot: Some Thistles and lodging but better than Monocrop
• 30% Triticale plot: Visibly less Lodging.
  At harvest he favoured the 30% Triticale plot but before
• 10%-20% plots were more favoured.
• No significant difference in yield
• Not sure how representative this years data is due to weather
• He is thinking of going higher with the % Triticale
• Slight yield hit on Peas in intercrops but not enough to be significant
• (PP) It is a lower yielding pea anyway, on my 2.6 ha organic system vs my neighbours conventional fields we yield the same.

Key learnings & Economics

• Plant team seems to work, will try higher rates (20-50%) Triticale but needs to consider the economics of this.
• Could use seed from this year to save money (Split peas in the Triticale won’t grow anyway)
• Yield penalty could be out weighed by combine costs.
  Is there anyway to measure time of Intercrops VS Monocrop?
• Using the intercrops for feed so don’t need to separate. No extra management time vs the monocrop beans

A number of group members were successfully funded for the 2018 DIVERSify Intercropping trials looking at a range of plant teams. Plant teams include: Wheat and beans, Carlin peas and triticale, beans and Spring OSR, peas and barley.

Each farmer will be trialling as follows:

Farmer A - Spring barley with crimson & berseem clover (2.5 ha) vs Spring barley monoculture (2.8 ha)
Farmer B – Spring beans with Spring wheat (2.8) vs Spring beans (2 varieties) (2.8 ha)
Farmer C – Winter wheat with white clover, aslike clover & trefoil (7.5 ha) vs Winter wheat monoculture (0.5-1 ha)
Farmer D – Winter beans & Spring wheat (1 ha) vs Winter beans monoculture (1 ha)
Farmer E – Peas & barley with vetch & grass (5 ha) vs Pea and barley (2 ha)
Farmer F – Spring beans with Spring OSR (4 ha) vs Spring beans (2 ha)
Farmer G 1 – Carlin peas with Spring triticale (4 ha) vs Carlin peas (1.8 ha)
Farmer G 2 – Fodder beat with buckwheat (3 ha) vs Fodder beat (0.23 ha)
Farmer H – Rye with beans (4 ha) vs rye monoculture (1.4 ha) and bean monoculture (1.4 ha)

Small trial plots have also been set up at the University of Reading Crops Research Unit. Four reps of x 6 treatments: Pea, Bean, OSR, Pea/OSR, Bean/OSR and an OSR/legume intercrop (to fill the 6th plot in the block) in 5m x 2m plots. There will also be 3 reps x 3 treatments of OSR, OSR/Barley and OSR/legume in 5m x 4m plots to look at the effect of intercropping on fleabeetle damage.

The Organic Research Centre also have wheat and bean, and wheat and lupin intercropping trials at this site.

This meeting identified the past experiences working with plant teams (complementary crops) within the group.

Example plant teams tried and effectiveness are as follows:

- Spring Wheat and Tundra Beans,
- Spring Barley and Peas (Unsuccessful),
- Peas and Oil Seed Rape (OSR),
- Chickpeas and Linseed (Unsuccessful),
- Clover and OSR alongside direct drilling.

Plant teams of interest for further trials were selected and discussed. It was noted that the type of plant team will depend on the farm environment e.g. soil type and weed burden. Plant team success will likely be measured at a single farm scale but the group will consider options for cross-farm comparisons of different crop combination 'working groups' e.g. cereal and legumes.

The group discussed what they would like to get out of the plant teams and why they are interested in trialling certain combinations. The first ideas are as follows:

- Clover undersown / companion cropped with a cash crop (to supress weeds, improve soil health, improve yield, improve water infiltration and soil structure).

- Beans and OSR (to increase yield, the two crops are easy to separate and have similar harvest dates).

- Clover with a cash crop (to improve soil health and reduce chemical usage).

- Beans and wheat (Reduce weeds in bean crop, and the wheat should not outcompete the beans).

- Legumes and buckwheat (To supress weeds and improve soil health and mineral availability).

- Vetch and Westwold, linseed and peas and yellow trefoil and spring barley (to increase diversity on farm and spread risk).

The group then discussed a potential trial plot intercropping OSR with beans and other cash crops, to be held at the University of Reading (to reduce pest risk in OSR).