Do legume-based intercrops improve soil fauna and soil microbial diversity? Example of the cowpea-cassava intercropping system in Northern Vietnam (Yen Bai Province)

Industrial agriculture has allowed food safety through the crop homogenization and the massive use of pesticides and chemicalfertilizers. This intensive agriculture has positively influenced the crop productivity but has also negatively affected the environment with direct consequences on soil health and productivity. The importance of the micro and macro organisms in the sustainability of soil fertility is widely recognized. Soil fauna represents 23% of the global fauna and contributes to most of the ecosystem services such as porosity, soil aggregation, control of the microbial activity and plant protection against pests and diseases. To mitigate the collateral effects of intensive agriculture on soil productivity in South East Asia, agro-ecological practices are currently promoted, including the use of legumes in intercropping systems. We studied the effect of the intercropping system cassava-cowpea (Vigna unguiculata L.) on the soil biotic compartment in Yen Bai province, a mountainous region in the North of Vietnam. Intercropping resulted in the increase of macro fauna richness and evenness. Intercropping system also significantly enhanced both diversity and abundance of soil micro fauna. The high throughput sequencing analysis of the microbial community showed that bacterial communities' abundance and richness were significantly higher in intercropping system than in mono-cropping fields. However, intercropping did not significantly affect the fungal communities and the soil parameters including pH and organic matter. Our results highlight the importance of the promotion of agro ecological practices such as legume intercropping systems in the Highlands in Northern Vietnam where the sustainability of the ecosystem is very fragile

The growth and yield of maize (Zea mays L.) and soyabeans (Glycine max. (L) Merrill) grown as intercrops : a thesis presented in partial fulfilment of the requirement for the degree of Master of Agricultural Science in Plant Science at Massey University

The effect of plant population maize (Zea mays L.) cultivar (Pioneer 3901) and AMT and Matara cultivars of soyabeans (Glucine max (L) Merill) grown together in an intercropping system was studied. In the experiment three rows of maize were sown at populations of 6, 8, 10 plants/m2 and three rows of soyabeans were planted between the rows of maize at either 50 or 75 plants/m2 replacing one of the three rows of maize. Plants were sampled for vegetative analysis during the growth of the crops and at final harvest. Total dry matter, grain yield and the components of yield and leaf area index were determined. Grain yield of maize increased from 794 to 1522 g/m 2 as the population of maize increased. However the yield of the maize was not affected by either the cultivar or the populations of the soyabeans grown among it. Grain yield and the component of yield of the intercropped soyabeans were not affected when population of maize in the mixture was increased. Matara produced higher yields than AMT when grown with maize and this was associated with production of more grain per plant and larger seeds. As the plant population of the soyabeans was increased the grain yield of Matara increased and up to 336.9 g/m2 was obtained, however the yield of AMT was not affected by a similar increase in plant population, possibily Matara had greater temporal difference and was more competative than AMT when grown in the mixture. Three methods were used to evaluate the yield of intercropped plots. These were the seed yield summed for both crops, Land Equivalent Ratio (LER) and a yield ratio based on maize. Although the results obtained depended on the method used all the three methods indicated intercropping could be more advantageous than growing maize and soya­ beans as pure stands. All the three methods indicated that the highest yield was obtained when the highest population of maize was combined with the highest population of soyabeans. Higher yields were obtained when Matara rather than AMT was grown in the intercropped plots

Horticulture agroforestry systems: a modelling framework to combine diversification and association effects

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Evaluating soil nitrate dynamics in an intercropping dripped ecosystem using HYDRUS-2D.

The competition mechanisms between crop species for water and nutrients, especially nitrate (NO3-N), in intercropping ecosystems are still poorly understood. Therefore, an experiment involving high (300 kg ha-1 for corn and 250 kg ha-1 for tomato), medium (210 kg ha-1 for corn and 175 kg ha-1 for tomato), and low (150 kg ha-1 for corn and 125 kg ha-1 for tomato) N-fertilizer applications (HF, MF, LF, respectively) was conducted in the corn and tomato intercropping ecosystem during 2014 (a calibration period for modeling) and 2015 (a validation period for modeling). The modified HYDRUS-2D code was used to analyze soil NO3-N concentrations (SNC) in the middle between corn rows (Pc), between corn and tomato rows (Pb), and between tomato rows (Pt), NO3-N exchange in the horizontal direction between different regions, NO3-N leaching from the corn, the bare, and the tomato region, and N uptake by crops. Simulated SNCs were in good agreement with measurements, with RMSE, NSE, and MRE of 0.01-0.06 mg cm-3, 0.75-0.98, and 8.7-19.1%, respectively, during the validation period (2015). Average SNCs in the 0-40 cm soil layer were different between Pc, Pt, and Pb. Intensive NO3-N exchange in the horizontal direction occurred during the second stage (Day After Sowing [DAS] 37-113 in 2014; DAS 29-120 in 2015). NO3-N exchange between the corn and bare regions was lower than between the tomato and bare regions due to smaller concentration gradients. However, in the vertical direction, NO3-N leaching from the corn region in both years was 4.1 and 8.8 times larger, respectively, than from the tomato region under HF since NO3-N mainly moved from the tomato region to the corn region. Our results reveal the competition between corn and tomato for N and provide a rationale for formulating and optimizing different fertilizer regimes for different crops in the intercropping ecosystem

Intercropping cereals and grain legumes: a farmer’s perspective

Intercropping cereals and grain legumes show potential for organic agriculture in many ways. However, the use of land equivalent ratio (LER) as a measure for calculating the cropping advantage of intercrops over sole crops is too simple: neglecting weed suppression, yield reliability, grain quality, and minimum profitable yield, which are all relevant fac-tors from a farmer’s perspective. Only when the crop selection for the mixtures is carefully done, and crops are grown on the right soil in the right rotation, can intercropping be made to profit

Weed management in grain legumes using an intercropping approach

Grain legumes benefit the farming system via symbiotic N2 fixation and subsequent residue incorporation contributing to soil fertility together with their effect as break-crop in cereal rich rotations. However, grain legumes are weak competitors towards weeds and consequently weeds constitute a major problem. Since the European policies for reducing the negative effects of agricultural plant production on the environment point to reductions in pesticide use (Mortensen et al., 2000), there is a requirement to further develop strategies to reduce weeds. Intercropping involves the simultaneous growing of several plant species in the same field and the cropping strategy is known to involve interspecific interferences increasing the use of plant growth resources in space and time (Ofori and Stern, 1987) improving crop competitive ability towards weeds (Hauggaard-Nielsen et al., 2001). The main objectives of the present study was to determine the effects of grainlegume-cereal intercropping on the weed biomass production as compared to the respective sole crops using successive harvests in a three-year field study

Meta-Analysis on grain yield effects of cereals-legume intercropping

Meta-Analysis on grain yield effects of cereals-legume intercroppin

The efficiency of a durum wheat-winter pea intercrop to improve yield and wheat grain protein concentration depends on N availability during early growth

Grain protein concentration of durum wheat is often too low, particularly in low-N-input systems. The aim of our study was to test whether a durum wheat - winter pea intercrop can improve relative yield and durum wheat grain protein concentration in low-N-input systems. A 2-year field experiment was carried out in SW France with different fertilizer-N levels to compare wheat (Triticum turgidum L., cv. Nefer) and pea (winter pea, Pisum sativum L., cv. Lucy) grown as sole crops or intercrops in a row-substitutive design. Without N fertilization or when N was applied late (N available until pea flowering less than about 120 kg N ha-1), intercrops were up to 19% more efficient than sole crops for yield and up to 32% for accumulated N, but were less efficient with large fertilizer N applications. Wheat grain protein concentration was significantly higher in intercrops than in sole crops (14% on average) because more N was remobilized into wheat grain due to: i) fewer ears per square metre in intercrops and ii) a similar amount of available soil N as in sole crops due to the high pea N2 fixation rate in intercrops (88% compared to 58% in sole crops)

The use of mixed species cropping to manage pests and diseases – theory and practice

This paper was presented at the UK organic research 2002 on behalf of colloquium of Organic Researchers (COR). Mixed species cropping is often perceived as a viable tool to increase on-farm biodiversity in organic agriculture and is a potentially important component of any sustainable cropping system. Apart from increasing total farm productivity, mixed species cropping can bring many important benefits such as improvement of soil fertility management and suppression of pests and/or diseases. In this sense it can be seen as performing different eco-services in the farm system. This paper discusses mixed cropping in this context while focusing on its potential and actual use as a tool to manage pests and diseases in organic farming systems

The effect of Intercropping on the Deep Root Development and Nutrient Uptake in a Sugar Beet – Chicory Mixture.

Sustaining an increasing human population with decreasing soil resources is a great challenge of the 21st century. Suboptimal availability of water and N are primary limitations to plant growth in the low-input agroecosystems in developing nations, whereas intensive fertilization at the cost of substantial environmental pollution is a problem in rich countries. The development of crops with greater rooting depth addresses these challenges. Deeper rooting improves water and nutrient uptake, which in turn reduces the need of application of external resources. In our study, we investigate the effect of intercropping on the deep root development and nutrient uptake in sugar beet – chicory mixture. The crops were chosen due to their deep roots and similar growing periods. We hypothesize that in the intercropping system one of the component crops develops roots below the root surface of the other crop, which results in deeper nutrient uptake in comparison to crops growing in pure stands. Crops will be grown in the field as monocultures and in mixture. Root growth will be monitored with minirhizotron method up to 4 m depth. Nutrient uptake will be studied using stable isotopes and ingrowth core methods. Additionally, root biomass estimation through DNA extraction from soil will be investigated. We expect that the results will help to answer the questions of whether the intercropping enhances deeper root growth and nutrient uptake in comparison to sole crops. With this knowledge, exploitation of the subsoil resources by deep roots would contribute to enhanced food production in a sustainable way. The study will start in spring 2018 and preliminary results will be presented