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Planting geometries directly affect crop yields in intercropping systems. Two different field experiments were conducted in 2012–2013 to analyze how different planting geometries in maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] relay strip intercropping systems at 2:2 maize‐to‐soybean affect yields. Maize plants were planted in narrow‐row planting patterns, whereas soybean was planted in wide rows. The effects of bandwidth, row spacing, plant spacing, and the distance between maize and soybean rows on crop yields were studied. Total intercrop yields were higher than those of sole crop maize and soybean, and the land equivalent ratios of the intercropping systems were above 1.3. The yield of the intercropped maize increased with bandwidth reduction at the same plant density, and similar results were found with increased maize narrow‐row spacing at the same bandwidth. Plant spacing had a dominant function when the bandwidth of the intercropped soybean was >200 cm. By contrast, the distance between maize and soybean rows had a dominant function when bandwidth was <200 cm. The optimum bandwidth and maize narrow‐row spacing in maize–soybean relay intercropping systems were 200 and 40 cm, respectively. These results suggest that the appropriate reduction in the spacing of the narrow maize rows and increase in the distance between maize and soybean rows could be used to achieve high yields in maize–soybean intercropping.

Intercropping advantage occurs only when each species has adequate time and space to maximize cooperation and minimize competition between them. A field experiment was conducted for two consecutive years between 2013 and 2014 to investigate the effects of maize and soybean relay strip intercropping systems on the uptake and utilization of nitrogen, phosphorus, and potassium. The treatments included “40:160” (T1, maize narrow and wide row spacing of 40 and 160 cm, where two rows of soybean with a 40 cm row were planted in the wide rows. The area occupation ratio of maize and soybean both were 50% of the every experimental block), “80:120” (T2, maize narrow and wide row spacing of 80 and 120 cm, the soybean planting was the same as T1 treatment. The area occupation ratio of maize and soybean were 60% and 40% of the every experimental block), “100:100” (T3, one row of maize and one row of soybean with a 100-cm row. The area occupation ratio of maize and soybean was the same as T1 treatment), sole cropping of maize (CK1, The area occupation ratio of maize was 100% of the every experimental block), and sole cropping of soybean (CK2, The area occupation ratio of soybean was 100% of the every experimental block). The results show that, compared with the sole cropping system (sole maize), the economic yields in T1, T2, and T3 treatments increased by 761, 536, and 458 kg·ha−1, respectively, and the biological yields increased by 2410, 2127, and 1588 kg·ha−1. The uptake and utilization of nitrogen, phosphorus, and potassium in T1, T2, and T3 treatments were significantly higher than those in sole crops, and the nutrient advantage is mainly due to nutrient uptake rather than nutrient use efficiency. The land equivalent ratio values in T1, T2, and T3 treatments were 1.43, 1.32, and 1.20, respectively. In particular, the economic and biological yield in T1 treatment exhibited potential as an intercropping pattern.

Yang (2017) Effect of narrow-row planting patterns on crop competitive and economic advantage in maize-soybean relay strip intercropping system,

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