•The improved PAR and Pn of maize ear leaves potentially increased the crop RUE of strip intercropped maize.•The improved PAR at soybean canopy top increased Pn, intercepted PAR, and partial LER of ...strip intercropped soybean.•The interspecific competition of system intercepted PAR adjusted the yield of intercrops and LER.•The LER of 1.42 was achieved in SI2 which was the leading level of the world.
Maize (Zea mays)-soybean (Glycine max) intercropping is popular in many developing countries because of its high land equivalent ratio (LER). However, very few studies have explored the reason of its high LER, and the relationships between light distribution and the variations in radiation use efficiency (RUE) and LER in different intercropping arrangements. In this study, we conducted field experiments with different row arrangements of intercropping patterns from 2013 to 2015. The three different strip intercropping (SI) row arrangements were 0.2 m, 0.4 m, and 0.7 m (SI1); 0.4 m, 0.4 m, and 0.6 m (SI2); and 0.6 m, 0.4 m, and 0.5 m (SI3) for maize row distance, soybean row distance, distance between maize and soybean rows, respectively. The results showed that, as compared to single row intercropping, the strip intercropping increased the PAR at top of soybean canopy by 1.42 (SI3), 1.67 (SI2) and 1.93 (SI1) times, and increased the PAR at maize leaves close to the ear by 1.02 (SI3), 1.11 (SI2) and 1.12 (SI1) times. Moreover, the increased PAR at crucial positions in SI potentially improved the photosynthetic rate (Pn) for maize leaves close to the ear and radiation use efficiency (RUE) of maize by 1.08 and 1.09 times (averaged by SI1, SI2 and SI3), respectively, and improved the Pn of leaves at top of canopy and intercepted PAR of soybean by 1.75 and 1.36 times (averaged by SI1, SI2 and SI3), respectively. Compared to monoculture, SI also enhanced the RUE of intercropped maize (by 1.18 times) and soybean (by 1.51 times), which compensated for the partial yield loss caused by decreased crop intercepted PAR. Overall, in SI, intercropped maize achieved 90% of the monoculture yield, and intercropped soybean achieved 47% of the monoculture yield. With the expanding gap width for growing soybeans under a fixed bandwidth (2 m), the increasing intercepted PAR of intercropped soybean alleviated the interspecific competition disadvantage of soybean, while the reduction of maize row width decreased the dominant interspecific competition of maize. By adjusting the distances, we suggest that the optimal gap width for growing soybeans is 1.6 m-1.8 m, and the best maize row distance is 0.4 m. The SI2 achieved LER of 1.42, representing the leading level in the world.
•A global meta-analysis was conducted on maize/soybean intercropping.•Average land equivalent ratio (LER) was 1.32 ± 0.02.•The average value of fertilizer nitrogen equivalent ratio (FNER) was ...1.44 ± 0.03.•Intercropping saved fertilizer due to concentrating production on less land with similar fertilizer N input per unit land.•Increasing N input scarcely changed LER and pLERmaize but significantly reduced intercropped soybean yield.
Intercropping exploits species complementarities to achieve sustainable intensification by increasing crop outputs per unit land with reduced anthropogenic inputs. Cereal/legume intercropping is a classical case. We carried out a global meta-analysis to assess land and fertilizer N use efficiency in intercropping of maize and soybean as compared to sole crops, based on 47 studies reported in English and 43 studies reported in Chinese. The data were extracted and analyzed with mixed effects models to assess land equivalent ratio (LER) of intercropping and factors affecting LER. The worldwide average LER of maize/soybean intercropping was 1.32 ± 0.02, indicating a substantial land sparing potential of intercropping over sole crops. This advantage increased as the temporal niche differentiation between the two species was increased by sowing or harvesting one crop earlier than the other as in relay intercropping, i.e. with only partial overlap of the growing periods of the two species The mean fertilizer N equivalent ratio (FNER) was 1.44 ± 0.03, indicating that intercrops received substantially less fertilizer N than sole crops for the same product output. These fertilizer savings are mainly due to the high relative maize yield and the lower N input in the intercrop compared to the input in sole maize. This meta-analysis thus shows that exploiting species complementarities by intercropping maize and soybean enables major increases in land productivity with less fertilizer N use. Both LER and FNER increased as the difference in growth duration increased for maize and soybean, but were not affected by fertilizer N rate. LER increased when soil organic matter increased but FNER did not change with soil organic matter.
•Row configurations significantly affect PAR distribution in maize-soybean relay intercropping system.•Aboveground interactions play an important contribution to intercrop advantages in maize-soybean ...relay intercropping.•Reducing the competitive ability of maize improves intercropping advantage in maize-soybean relay intercropping system.
Aboveground and belowground interactions are crucial in the over-yielding of intercropping systems. However, the relative effects of aboveground and belowground interactions on yields of intercrops in maize (Zea mays L.) and soybean Glycine max (L.) Merr. relay intercropping systems are still unclear. Field experiments, including measurements of biomass, grain yield, and photosynthetic parameters, were conducted in 2013–2014 to analyze the advantages and effects of aboveground and belowground of interspecies interactions on yield. To analyze the aboveground interactions of intercrops for light interception, this study adopted three different row configurations (P1) “160cm+40cm” and (P2) “120cm+80cm” maize wide-narrow row planting, where two rows of soybean with a 40-cm row width were planted in the wide rows, and (P3) “100cm +100cm” maize equal-row planting, where one row of maize and one row of soybean with a 50-cm spacing between the adjacent rows of both crops. Moreover, to identify interspecies belowground competition, no root separation (R1) and root separation (R2) were employed between adjacent maize and soybean rows.
The photosynthetically active radiation (PAR) transmittances of maize wide-row were significantly higher than those of maize narrow-row at the sixth leaf stage (jointing stage), twelfth leaf stage (bell stage), and tasseling stage. Specifically, PAR transmittances decreased as maize narrow-row spacing increased. No significant differences in the PAR transmittances of maize narrow-row or wide-row were found between the R1 and R2 conditions. Similarly, no significant differences between intercrop biomass and grain yield were observed between the R1 and R2 conditions. By contrast, different row configuration treatments exhibited significant differences in biomass (whole growth period for soybean and after tasseling stage for maize), grain yield and photosynthetic parameters of intercrops. These results implied that aboveground interactions, such as mutual shading, have more significant contributions to intercrop advantages than belowground interactions. In addition, the intercropped maize yields increased as maize narrow-row spacing (from P1 to P3 treatment) increased. However, contrasting trends were found for intercropped soybean yield and land equivalent ration (LER). No significant differences in LER were observed between R1 and R2 conditions in different row configurations. P1 treatment exhibited the maximum LER (1.64 for 2013 and 1.83 for 2014) and mixed yield (7430kgha−1 for 2013 and 9559kgha−1 for 2014), but the lower maize yield compared with P2 and P3 treatments. This result suggested that reducing the competitive ability of maize while increasing that of soybean significantly improves intercropping advantage in maize-soybean relay intercropping systems.
Satisfying the nutritional needs of a growing population whilst limiting environmental repercussions will require sustainable intensification of agriculture. We argue that intercropping, which is the ...simultaneous production of multiple crops on the same area of land, could play an essential role in this intensification. We carried out the first global meta-analysis on the multifaceted benefits of intercropping. The objective of this study was to determine the benefits of intercropping in terms of energetic, economic and land-sparing potential through the framework of the stress-gradient hypothesis. We expected more intercropping benefits under stressful abiotic conditions. From 126 studies that were retrieved from the scientific literature, 939 intercropping observations were considered. When compared to the same area of land that was managed in monoculture, intercrops produced 38% more gross energy (mean relative land output of 1.38) and 33% more gross incomes (mean relative land output of 1.33) on average, whilst using 23% less land (mean land equivalent ratio of 1.30). Irrigation and the aridity index in non-irrigated intercrops did not affect land equivalent ratio, thereby indicating that intercropping remains beneficial, both under stressful and non-stressful contexts concerning moisture availability. Fertilisation and intercropping patterns (rows and strips vs. mixed) did not affect land equivalent ratio. Although intercropping offers a great opportunity for intensification of existing agricultural lands, many challenges need to be tackled by experts from multiple disciplines to ensure its feasible implementation.
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•Global productivity potential of intercropping was determined using a meta-analysis.•Global land equivalent ratio of intercropping was 1.30.•Land equivalent ratio of intercropping did not vary through a water stress gradient.•Intercropping increases gross energy production by 38%.•Intercropping increases gross incomes by 33%.
•Meta-analysis of the intercropping literature shows that average LER is 1.22±0.02.•An index (TND) is proposed to quantify temporal niche differentiation in intercrops.•LER increases with TND in ...C3/C4 intercrops but not in C3/C3 intercrops.•LER decreases with rate of N fertilizer at low TND.•The negative effect of nitrogen fertilizer on LER is alleviated by increasing TND.
Sustainable intensification of agriculture is needed to meet higher future food demands while mitigating agriculture’s ecological footprint. Intercropping is a strategy for increasing agricultural productivity per unit land that is based on ecological mechanisms for improved resource capture. No quantitative synthesis has been made on the effect of intercrop system properties and species trait combinations on intercrop productivity. Here we use meta-analysis of the intercropping literature to study how the productivity of mixed systems is affected by intercrop system design and species traits. We focus on the effects of temporal niche differentiation between species, intercropping pattern, relative densities, the use of C3 and C4 species and the rate of nitrogen fertilizer. Land equivalent ratio (LER) is used as index for assessing the relative productivity of a mixed system as compared to sole crops. Average LER was 1.22±0.02, and no differences in LER were found between the 50 most highly cited studies and a random sample from the literature, indicating that high LERs in highly cited papers are representative of the entire literature. Temporal niche differentiation contributed substantially to high LER in systems combining a C3 and C4 species, but not in systems based on C3 species mixtures. The amount of N fertilizer interacted positively with the effect of temporal niche differentiation on LER. The intercropping literature is dominated by studies on cereal/legume mixtures. However, the few studies on C3 cereal/C4 cereal mixtures indicate these mixtures have high LER.
Substantial improvements in land use efficiency in agriculture may be obtained by using mixtures, particularly C3/C4 mixtures. Thus, enhanced within-field crop diversity can make an important contribution to sustainable increases in food production.
Intercropping improves crop productivity in dryland farms, but little information is available on its application to irrigated land. Therefore, a three-year field trial was conducted to compare two ...maize-soybean strip-intercropping planting patterns (two-rows of maize intercropped with two-rows of soybean 2M2S or -three rows of soybean 2M3S) were studied with sole maize (SM) and sole soybean (SS) systems. Our results showed that wider-strips of soybean grown as 2M3S had significantly higher leaf area index (LAI; 19%), total dry matter accumulation (TDM; 15%), and grain yield (21%) than the narrower 2M2S strips; this is likely related to the reduced effects of maize shading on soybean. Slightly decreased LAI (4%), TDM (8%), and grain yield (5%) of maize were found in 2M3S. On average, intercropped maize and soybean produced 80% and 52% in 2M2S and 76% and 63% in 2M3S compared to SM and SS yields, respectively, demonstrating the dominance of maize over soybean when intercropped. Similarly, maize was a stronger competitor for water than soybean, with partial water equivalent ratio of 0.81 in 2M2S and 0.78 in 2M3S, while that of soybean was 0.54 in 2M2S and 0.66 in 2M3S. In the intercropping systems, the land equivalent ratio ranged from 1.31 to 1.45, and the water equivalent ratio ranged from 1.32 to 1.49, exhibiting that maize-soybean strip-intercropping is a productive strategy to maximize water use efficiency. The results suggest that the maize-soybean strip-intercropping system may be a productive and sustainable strategy to improve the water use efficiency and land productivity under irrigated conditions. This strategy could benefit agriculture with cleaner, and more efficient production under a global scenario of constrained land and water resources. However, more studies are needed to evaluate the feasibility of intercropping systems in various growing conditions.
•Maize-soybean strip intercropping system shows great potential with irrigation in the semi–arid region.•The average LER (1.37) of intercropping systems demonstrates high relative LUE than sole crops.•Maize was a stronger competitor for land and water than soybean in intercropping systems.•The mean WER (1.40) of intercropping systems shows high relative WUE compared to sole crops.
•A multi-scale sensitivity analysis was performed including modifications from module to string to array.•Various topologies of fixed bifacial agrivoltaic arrays were simulated.•Design trade-offs and ...potential synergistic effects were examined.•The E-W wings agrivoltaic array layout was proposed with an extended front glass cover.•By adopting a translucent cover, blueberries photosynthesized effectively under shade.
To safeguard future renewable energy and food supply the use of agrophotovoltaic (APV) systems was investigated, which enable simultaneous production under the same piece of land. As conventional photovoltaic (PV) array topologies lead to unfavourable conditions for crop growth, the application of APV is limited to areas with high solar insolation. By optimizing the APV array’s design, compatibility with various climates and crop species can be attained. Therefore, the aim of this research was to establish a multi-scale modelling approach and determine the optimal topology for a medium-to-large-scale fixed bifacial APV array. Three main topologies were analyzed under the climate of Boston, USA: S-N facing, E-W wings, and E-W vertical. For each topology, respectively, specific yield was amplified by 39%, 18%, and 13% in comparison to a conventional monofacial ground mounted PV array. E-W vertical is more appropriate for permanent crop species, while S-N facing necessitates the cultivation of shade tolerant crops during summer as electricity generation is prioritized. The E-W wings APV topology combines the best of both; light is distributed homogeneously, and crops are effectively shaded at noon. To promote the growth rate of blueberries under shade, customized bifacial modules were integrated (arranged as the E-W wings). Land productivity enhanced by 50%, whereas electrical AC yield reduced by 33% relative to the conventional and separate production. Through this holistic approach, it is possible to achieve a comprehensive understanding of the limitations and potential synergies associated with the dual use of land; ultimately, encouraging the transition of the agricultural sector into sustainability.
•Wolfberry/ Gramineae intercropping could improve productivity as evidenced by a significant increase in the land equivalent ratio (LER).•Wolfberry fruit quality was significantly improved under ...intercropping, which shows up in fruits carotenoid, flavonoid, total sugar and ascorbic acid content increased.•Potassium and nitrogen were the nutrients that most affected the bacterial community, and all soil enzymes corelated with bacterial community composition, particularly under intercropping mode.•Wolfberry/ Gramineae intercropping could alter the soil bacterial community composition which reflects changes in soil properties and enzyme activities.
The intercropping of shrubs with Gramineae species has been used widely to increase productivity and sustainability in modern agriculture. However, there have been few studies of intercropping of Wolfberry shrubs (Lycium barbarum) and it is cultivated mostly by clean tillage. In this study, we measured land productivity, crop yield and quality, and soil properties when L. barbarum was intercropped with Gramineae plants compared to when grown in a monoculture with clean tillage. The results showed that Wolfberry/ Gramineae intercropping improved productivity and fruit quality as evidenced by a significant increase in the Land Equivalent Ratio (LER) and the content in the fruit of carotenoid, flavonoid, total sugar and ascorbic acid. The nutrient content and enzyme activity of rhizosphere soils were higher under intercropping. The physical properties of the soil also improved with increased soil moisture, available potassium, available phosphorus and total nitrogen. The effect of intercropping on bacterial diversity was greater than that on fungal diversity, especially alpha diversity as shown by the Shannon Index, although both groups were markedly altered by intercropping. Binding spatial ordination analysis demonstrated that potassium and nitrogen were the nutrients that most affected the bacterial community, and all soil enzymes corelated with bacterial community composition. Collectively, these results suggest that intercropping of L. barbarum with Gramineae plants alters the soil bacterial community composition which reflects changes in soil properties and enzyme activities. Our findings show how to improve Wolfberry productivity and they provide insights into the mechanisms underlying healthy, biodiverse soils in agroecosystems.
Increasing land-use conflicts call for the development of land-use systems that reconcile agricultural production with the provisioning of multiple ecosystem services, including climate change ...mitigation. Agroforestry has been suggested as a global solution to increase land-use efficiency, while reducing environmental impacts and economic risks for farmers. Past research has often focused on comparing tree-crop combinations with agricultural monocultures, but agroforestry has seldom been systematically compared to other forms of land-use diversification, including a farm mosaic. This form of diversification mixes separate parcels of different land uses within the farm. The objective of this study was to develop a modelling approach to compare the performance of the agroforestry and farm mosaic diversification strategies, accounting for tree-crop interaction effects and economic and climate uncertainty. For this purpose, Modern Portfolio Theory and risk simulation were coupled with the process-based biophysical simulation model WaNuLCAS 4.0. For an example application, we used data from a field trial in Panama. The results show that the simulated agroforestry systems (Taungya, alley cropping and border planting) could outperform a farm mosaic approach in terms of cumulative production and return. Considering market and climate uncertainty, agroforestry showed an up to 21% higher economic return at the same risk level (i.e. standard deviation of economic returns). Farm compositions with large shares of land allocated to maize cultivation were also more severely affected by an increasing drought frequency in terms of both risks and returns. Our study demonstrates that agroforestry can be an economically efficient diversification strategy, but only if the design allows for economies of scope, beneficial interactions between trees and crops and higher income diversification compared to a farm mosaic. The modelling approach can make an important contribution to support land-use decisions at the farm level and reduce land-use conflicts at the landscape level.
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•Agroforestry and a farm mosaic diversification approach are compared in terms of economic efficiency.•The approach accounts for economic and climate uncertainty.•A process-based growth model is coupled with Modern Portfolio Theory.•Agroforestry can compete with a farm mosaic system if it allows for beneficial tree-crop interactions and economies of scope.•Under high risk aversion a farm mosaic diversification system may be preferable.
•Potato/vetch intercropping is tested as a sustainable cropping system.•Vetch was a stronger competitor for water with partial water equivalent ratio of 0.83.•Land equivalent ratio of 1.30 ...demonstrates high relative land use efficiency compared to sole crops.•Water equivalent ratio of 1.29 demonstrates high relative water use efficiency compared to sole crops.•Spatio-temporal complementarity for water use makes this a productive and resilient cropping system for semi-arid conditions.
Protection from soil erosion and efficient use of water are vital to sustainable dryland potato production in semi-arid regions. Introducing legumes into semi-arid agricultural systems as intercrops improves soil quality due to biological nitrogen fixation and reduced wind erosion as a result of better soil cover, but the consequences of introducing legumes for the water use efficiency of the crop system are less predictable. Here we carried out field experiments from 2014 to 2017 in Inner Mongolia, China. We compared a rotational intercropping system of potato (Solanum tuberosum L.) and hairy vetch (Vicia villosa) with monocultures of potato and hairy vetch and quantified crop yield, water use efficiency and land productivity. While the relative density (the ratio of plant density in intercrop and the density in sole stand) of both crops in the intercropping was 0.5, the average relative yield of the potato over four years was 0.43, but that of the vetch was 0.87, indicating dominance of the vetch in the intercropping system. Land and water equivalent ratios, defined as the area of land or amount of water that would be needed in single cropping to achieve the same yield as in intercropping, averaged to 1.30 and 1.29 over the years, respectively, indicating high relative land and water productivity of potato/hairy vetch intercropping compared to monocultures. Vetch was a stronger competitor for water than potato with a partial water equivalent ratio of 0.83. We conclude that the potato/vetch intercropping system improves land productivity and system level water use efficiency under the rain-fed semi-arid conditions of the study site. These results are useful to optimize cropping systems for regional sustainability with consideration of both arable crop production (potato) and provision of fodder for animal husbandry (vetch).
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