Optimum strip width increases dry matter, nutrient accumulation, and seed yield of intercrops under the relay intercropping system

Abstract

Strip width management is a critical factor for producing higher crop yields in relay intercropping systems. A 2-year field experiment was carried out during 2012 and 2013 to evaluate the effects of different strip width treatments on dry-matter production, major-nutrient (nitrogen, phosphorus, and potassium) uptake, and competition parameters of soybean and maize in relay intercropping system. The strip width (SW) treatments were 0.40, 0.40, and 0.40 m (SW1); 0.40, 0.40, and 0.50 m (SW2); 0.40, 0.40, and 0.60 m (SW3); and 0.40, 0.40, and 0.70 m (SW4) for soybean row spacing, maize row spacing, and spacing between soybean and maize rows, respectively. As compared to sole maize (SM) and sole soybean (SS), relay-intercropped maize and soybean accumulated lower quantities of nitrogen, phosphorus, and potassium in all treatments. However, maize in SW1 accumulated higher nitrogen, phosphorus, and potassium than SW4 (9%, 9%, and 8% for nitrogen, phosphorus, and potassium, respectively). Soybean in SW3 accumulated 25% higher nitrogen, 33% higher phosphorus, and 24% higher potassium than in SW1. The improved nutrient accumulation in SW3 significantly increased the soybean dry matter by 19%, but slightly decreased the maize dry matter by 6% compared to SW1. Similarly, SW3 increased the competition ratio value of soybean (by 151%), but it reduced the competition ratio value of maize (by 171%) compared to SW1. On average, in SW3, relay-cropped soybean produced 84% of SS seed yield and maize produced 98% of SM seed yield and achieved the land equivalent ratio of 1.8, demonstrating the highest level in the world. Overall, these results suggested that by selecting the appropriate strip width (SW3; 0.40 m for soybean row spacing, 0.40 m maize row spacing, and 0.60 m spacing between soybean and maize rows), we can increase the nutrient 2 of 14 | RAZA et Al.

Strip-width determines competitive strengths and grain yields of intercrop species in relay intercropping system

“…Consequently, the soybean plants received more PAR-transmittance in T 2 compared to that of in treatment T 1 . These results are in agreement with the previous findings in which researchers have revealed that the spacing of 60 cm between the rows of intercrop species significantly reduced the maize shade by allowing more sunlight to penetrate to the soil surface 22 . Overall, these results exhibit that the selection of appropriate inter-row spacing is critical in improving the PAR-transmittance of soybean in MSR.…”

“…Although, in this study, we did not measure the effect of intercropping on water use of intercrop species in MSR; however, in a previous study (Rahman et al, 2017), it has been confirmed that maize and soybean utilized water more efficiently in medium-strips compared to the maize and soybean plants in narrow-strips in MSR 4 . Similarly, the inter-row spacing of 60 cm in MSR improved the uptake of nitrogen (by 25%), phosphorus (by 33%), and potassium (by 24%) in soybean compared to the inter-row spacing of 40 cm in MSR through the efficient exploitation of the biological potential for nutrient acquisition 22 . In wheat-fababean intercropping system, wheat roots uptake more nitrogen than faba bean from the rhizosphere and decrease the availability of nitrogen for fababean, which increased the percentage of nitrogen fixation in fababean 36 .…”

“…Such advantages of cereal-legume intercropping can be achieved through a maize/soybean relay intercropping system, especially in those areas where the growing season is too short for double cropping 19 . The maize/soybean relay intercropping system (MSR) is the best intercropping system in yield stability 20 , resource utilization 21 , and economic profit 22 . In MSR, maize yield is often equal or sometimes higher than the sole maize yield 23 .…”

“…Nevertheless, tradeoffs between intercrop species exist in MSR 22 , 26 , 27 . In many past reports, scientists have reported that soybean suffers from heavy maize shading, especially during the co-growth phase 13 .…”

The fingerprints of climate warming on cereal crops phenology and adaptation options

“…Nevertheless, optimum planting geometry could improve resource use efficiencies in crops through proper crop phenology, producing more leaf area and ultimately more favorable yield components and yield in cereal crops in all climatic conditions 251,252 . Planting geometry affects solar radiation interception, canopy coverage, crop growth rate and biomass accumulation 215,[253][254][255][256][257][258] . Furthermore, with optimum planting geometry, total dry matter production and ultimately grain yield increase was mainly due to more photo-assimilates 252 .…”