Investigating crop diversity for agroecosystem services: the impact of strip cropping in Dutch organic arable systems

Field experiment 7, the Netherlands

Figure 1: Experimental design of crop diversity trial in 2022. Source: Dirk van Apeldoorn, WUR

Figure 2: Pixelcropping plot in mid June 2021. Source: Dirk van Apeldoorn, WUR

Trial location and duration

Location: Wageningen University Droevendaal Organic Experimental and Training Farm, Wageningen, NL (51°59'30" N 5°39'50"E)

Trial duration: 2018-ongoing

Objectives and research question

The main objective of field experiment 7 is to examine the effects of and interactions between three dimensions of field-level crop diversification (temporal, spatial, and genetic) on the delivery of agroecosystem services in Dutch arable systems. Our focus is on strip cropping: the practice of growing two or more species in alternate, multi-row strips wide enough to allow independent cultivation but narrow enough to support ecological interaction. We hypothesize that re-introducing diversity within the field via strip cropping can help to support and regulate agroecosystem services without reducing yields. We test this by monitoring yield; crop quality; pest, disease and weed control; associated biodiversity; and soil parameters.

Experimental design

The experiment consists of three replicates of 63 x 54 m strip blocks for each of three crop pairs, and since 2021 one large-scale reference monoculture for each crop of 66 x 72m (Figure 1). The experiment is laid out in an incomplete block design between fields. In fields 1-3, treatments follow a randomized complete block design. Strip dimensions are 3 m x 54 m. The six-year rotation is based on the dominant crops produced by organic growers in the Netherlands and local constraints: cabbage—barley—potato—oat—pumpkin—grass. Crops are planted either as pairs in adjacent strips or alternating next to each other. Within the pairs three treatments are tested (Table 1). As a futuristic option, “pixel cropping” is also tested (see Table 1). All crops in the experiment are managed according to Dutch organic standards.

Table 1: Treatments tested at FE7, Wageningen, NL

Figure 3: Potato harvest, preventing compaction due to smart use of strip neighbours. The heavy tipper drives over the grass strip. Source: Dirk van Apeldoorn, WUR

Main findings and highlights

Yield variation between years is reduced by distribution of strips across more fields.
Yields were similar in all stripcropping treatments and the same or slightly lower in comparison to the references
Potatoes in stripcropping treatments had lower severity of potato late blight and fewer Colorado beetles than the references
Increasing the number of crops in the same plot (STRIP_ROT and PIXEL) resulted in a higher number of different insect species present.
The natural parasitism rate is higher in all stripcropping treatments than the references.

Main challenges

Strip design limits options for effective tillage causing excessive use of a cultivator.
Irrigating separate crops in strips reduces efficiency
Plant-based fertilization was more complicated and expensive to arrange.
Weather extremes call for new adaptive crops but this is constrained by market and trial relevance for farmers