Speaker
Description
Introduction
Intercropping is an increasingly popular management strategy to simultaneously support biodiversity, ecosystem services, and yields in agricultural systems. Nevertheless intercropping studies that look at both yield and ESS, such as pest control, are less common and without them it is difficult to find management that works for both farmers and the environment. The objectives of this study were to test several spatial arrangements of soy and winter wheat, row-relay, wide strip, and patch cropping and understand their yield and pest control potential. We hypothesized that the diversified treatments would support more natural enemies and fewer pests than the sole cropping while maintaining similar yields.
Materials & methods
We used an on-farm study in 2022 and 2023 to test how different forms of spatial diversification of soy and winter wheat can affect pest abundance, pest predation, natural enemies, and yields in Eastern Germany. We specifically studied three types of diversified systems compared to conventional sole cropping - row relay intercropping, wide strip cropping (12x150m), and patch cropping (72.5*72.5m). Crops were managed conventionally with input from the farmer. We monitored pests at wheat flowering, collected ground dwelling carabid beetles and spiders with pitfall traps in May and June, and measured predation rates with aphid predation cards installed in the field 3 times per year. Yield was measured with a combine harvester.
Results
We found that strip cropping generally supported the highest levels of carabid abundance both years and spider abundance in 2022 while producing equivalent, or higher, yields to the sole cropping. Soy and wheat strips had more beetles than their corresponding soy and wheat patches both years and the cropping treatments supported significantly different community compositions. The relay system failed due to insufficient precipitation but supported intermediate levels of natural enemy abundance as well as the highest carabid species richness as measured by the Chao1 index. The results of patches were mixed with yields and abundances either equivalent or lower than the strips and reference treatments. We found no effect of cropping treatment on aphid abundance but overall aphid infestation levels were very low both years and not correlated to natural enemy abundance. As for pest predation, strip cropping had a 51% (2022) and 36% (2023) increase in aphid predation rates compared to wheat patches and 86% and 10% increase compared to the reference wheat.
Discussion
We found that strip intercropping maintained ecological benefits, higher carabid abundance and aphid predation rates, with no yield penalties to the farmers with similar strip yield outcomes found in Canada (Labrie et al., 2016). Strips were likely able to maintain high yields because they are managed identically to their respective sole crop, they act as narrow fields and thus do not require additional driving and can handle pesticides that mixed relay cropping can not. Wide strips may support more natural enemies than patch or sole cropping due to the higher area:border ratio of strips as carabids and spider activity is often higher at edges than field centers (Ávila et al., 2017; Zhao et al., 2013) likely due to increased spatial-temporal resource availability at the edges. While some diversified systems did not perform as well as sole cropping, the strip cropping results show the potential of the system for farmers to diversify their farms in a manner that involves no additional machinery and little additional work.
| Keywords | carabids; spiders; pesticide reduction; crop diversification; IPM |
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