RESULTS

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Strip cropping increases yield and turnover

Multi-year research at ERF BV (The Netherlands) shows higher yield and turnover in strip cropping. What does this company specific strip cropping system look like? And what can farmers learn from this?

Strip cropping fields are increasingly common in Dutch arable farming, but which crops grow optimally side by side? This question was central to the multi-year research conducted for foundation Hemus on the organic arable farm ERF in Zeewolde (the Netherlands). Researchers at Wageningen University followed the crops in cooperation with foundation Hemus in a three-year study on a 64-hectare organic plot. On this plot, ERF grows eight crops in the same crop rotation of grass clover, celeriac, broccoli, oats, onion, parsnip and potato in six-metre-wide strips and, for comparison, in full-field blocks of two hectares. The aim? To see whether certain crop combinations in strip cropping increase yield and turnover or harm them.

Productivity

What is the effect of strip cropping on yield and do neighbouring crops play a role in it? In the study, we were eventually able to examine six crops, each located next to five different neighbouring crops. The study design not only allows us to look at the effect of strip cropping on yield, but also allows us to zoom in on the effects of the five different neighbouring crops for each crop. First, yields from the middle rows of strips were compared with yields from monoculture fields. Second, effects of neighbouring crops were examined by comparing yields from the edge rows of strips with the middle rows.

Answers to the question of whether strip cropping has an effect on yield are shown in Figure 1. Comparing the yield of the six crops in strip cropping with the full-field plots, the effect we see differs for each crop. Whereas the yields of field bean (+32%) and parsnip (+41%) are positively affected by strip cropping, potato and celeriac react neutrally and we see lower yields for oats (-6%) and onion (-10%) in strip cropping. When celeriac or broccoli were next to potato strips, we saw a positive effect on potato yield (+15% and +38%, respectively). For other crops, no effects of neighbouring crops were observed.

Our conclusion? Strip cropping by itself can increase yields. What combination of crops you grow can potentially add further yield increases. Although we saw that some crops had a bigger yield increase than others, the harvest weight for all crops combined went up by eight per cent. Higher yields can be translated into land use: strip cropping provides between five and 10 per cent land savings compared to full-field cropping. This space can be used for natural elements such as flower strips or hedges.

Viable alternative to full-field cultivation

Strip cropping is often seen as a system that requires extra labour. This constitutes one of the barriers to adopting strip cropping. Is it nevertheless an alternative to organic full-field cultivation? The increase in labour is caused, for instance, by complexity of planning and having to drive back and forth between fields more often. One way to test the viability of strip cropping is to calculate when the increase in yield can pay for the increase in labour. For Hemus' system in collaboration with ERF, we looked at how much the increase in yield could offset any increase in labour. The yield increase brought a higher turnover of €590 per hectare. This turnover can pay for an increase in labour of 24%. These are the results of one tested design. Other designs of crop combinations in strip cropping showed similar results and even higher turnover up to 759 euros per hectare. This means that despite a possible increase in labour in strip cropping, the increase in harvest and turnover can cover these costs.

What's next?

This three-year study by Hemus and ERF shows that when looking at all crops together, the effects of strips on yield are positive. Even if yields of some crops or crop combinations are lower than full-field cultivation. Moreover, it shows that it is more important to put emphasis on increasing crop diversity at the total plot level than on optimising neighbouring crops in a system with six-metre-wide metre strips. See also the box with tips for designing your strip cropping system.

This text previously appeared in EkolandText: Anna de Rooij, Hilde Faber, Dirk van Apeldoorn, Stella D. Juventia.