Soybean maize strip intercropping:A solution for maintaining food security in China

The practice of intercropping leguminous and gramineous crops is used for promoting sustainable agriculture,optimizing resource utilization,enhancing biodiversity,and reducing reliance on petroleum products.However,promoting conventional intercropping strategies in modern agriculture can prove challenging.The innovative technology of soybean maize strip intercropping(SMSI)has been proposed as a solution.This system has produced remarkable results in improving domestic soybean and maize production for both food security and sustainable agriculture.In this article,we provide an overview of SMSI and explain how it differs from traditional intercropping.We also discuss the core principles that foster higher yields and the prospects for its future development.

Coordinated responses of leaf and nodule traits contribute to the accumulation of N in relay intercropped soybean

Maize(Zea mays L.)-soybean(Glycine max L.Merr.)relay intercropping provides a way to enhance land productivity.However,the late-planted soybean suffers from shading by the maize.After maize harvest,how the recovery growth influences the leaf and nodule traits remains unclear.A three-year field experiment was conducted to evaluate the effects of genotypes,i.e.,supernodulating(nts1007),Nandou 12(ND12),and Guixia 3(GX3),and crop configurations,i.e.,the interspecific row spacing of 45(I45),60(I60),75 cm(I75),and sole soybean(SS),on soybean recovery growth and N fixation.The results showed that intercropping reduced the soybean total leaf area(LA)by reducing both the leaf number(LN)and unit leaflet area(LUA),and it reduced the nodule dry weight(NW)by reducing both the nodule number(NN)and nodule diameter(ND)compared with the SS.The correlation and principal component analysis(PCA)indicated a co-variability of the leaf and nodule traits in response to the genotype and crop configuration interactions.During the recovery growth stages,the compensatory growth promoted soybean growth to reduce the gaps of leaf and nodule traits between intercropping and SS.The relative growth rates of ureide(RGR_U)and nitrogen(RGR_N)accumulation were higher in intercropping than in SS.Intercropping achieved more significant sucrose and starch contents compared with SS.ND12 and GX3 showed more robust compensatory growth than nts1007 in intercropping.Although the recovery growth of relay intercropping soybean improved biomass and nitrogen accumulation,ND12 gained a more significant partial land equivalent ratio(pLER)than GX3.The I60 treatment achieved more robust compensation effects on biomass and N accumulation than the other configurations.Meanwhile,I60 showed a higher nodule sucrose content and greater shoot ureide and N accumulation than SS.Finally,intercropping ND12 with maize using an interspecific row spacing of 60 cm was optimal for both yield advantage and N accumulation.

Alternate cotton-peanut intercropping:a new approach to increasing productivity and minimizing environmental impact

Recent publications have highlighted the development of an alternate cotton-peanut intercropping as a novel strat-egy to enhance agricultural productivity.In this article,we provide an overview of the progress made in the alternate cotton-peanut intercropping,specifically focusing on its yield benefits,environmental impacts,and the underlying mechanisms.In addition,we advocate for future investigations into the selection or development of appropriate crop varieties and agricultural equipment,pest management options,and the mechanisms of root-canopy interactions.This review is intended to provide a valuable reference for understanding and adopting an alternate intercropping system for sustainable cotton production.

Assessing the Efficacy of Wheat-Soybean Based Intercropping System at Different Plant Densities in Bambili, Cameroon

Wheat is one of the most important cereals in the world, serving as a staple for millions globally. In the wake of the geopolitical crisis between Russia and Ukraine, it has become incumbent for many countries to invest in wheat production. Improving cropping systems for wheat production is paramount. Intercropping cereals with legumes has tremendous advantages. Therefore, this study was designed to optimize wheat production by intercropping it with soybean at different densities. Between March and August 2023, a randomized complete block design trial was conducted in Bambili, North West of Cameroon with treatments T1 (wheat monocrop at 200,000 plants ha−1), T2 (soybean monocrop at 250,000 plants ha−1), T3 (200,000 wheat and 125,000 soybean ha−1), T4 (100,000 wheat and 250,000 soybean ha−1), T5 (200,000 wheat and 250,000 soybean ha−1) and T6 (100,000 wheat and 125,000 soybean ha−1). Results revealed that growth parameters of wheat were not significantly influenced by monocrop or intercrop. The yield of wheat was significantly higher in the monocrop than the intercrop treatments, with slight variation amongst the intercrop treatments. Soybean yield was higher in the monocrop than in the intercrop, with no variations amongst the intercrop treatments. Only the land equivalence ratio (LER) for T5 was greater than 1.0. The competitive ratio for T5 was 0.54 for wheat and 1.90 for soybean, comparatively lower than the other monocrop treatments. Intercropping wheat and soybean at 200,000:250,000 ratio is recommended.

Legume Green Manure and Intercropping for High Biomass Sorghum Production

Before the advent of cheap, synthetic fertilizers, legumes were commonly used as green manure crops for their ability to fix atmospheric nitrogen (N). A three-year study at Overton, TX examined legume integration into high-biomass sorghum (Sorghum bicolor L.) production systems on a Lilbert loamy fine sand recently cultivated after a fertilized bermudagrass [Cynodon dactylon (L.) Pers.] pasture. In this split-split plot design, ‘Dixie’ crimson clover (Trifolium incarnatum L.) and ‘Iron and Clay’ cowpea (Vigna unguiculata L.) were integrated into a high-biomass sorghum production system to evaluate impacts on N concentration, C concentration, and yield of high-biomass sorghum and their impacts on soil total N and soil organic carbon (SOC). Main plots were split into crimson clover green manure (CLGM) and winter fallow (FALL) followed by three sub-plots split into warm-season crop rotations: cowpea green manure (CPGM), cowpea-sorghum intercrop (CPSR), and sorghum monocrop (SORG). Three N fertilizer treatments (0, 45, 90 kg N∙ha−1) were randomized and applied as sub-sub plots. The CLGM increased (P sorghum biomass yield (16.5 t DM∙ha−1) 28% in year three but had no effect in the first two years. The CPSR treatment reduced sorghum yield up to 62% compared to SORG;whereas CPGM increased sorghum yield 56% and 18% the two years following cowpea incorporation. Rate of N fertilizer had no effect on sorghum biomass yield. Decrease in SOC and soil N over time indicated mineralization of organic N and may explain why no N fertilizer response was observed in sorghum biomass yield. Cowpea showed strong potential as a green manure crop but proved to be too competitive for successful intercropping in high-biomass sorghum production systems.

Millet/peanut intercropping at a moderate N rate increases crop productivity and N use efficiency,as well as economic benefits,under rain-fed conditions

Cereal and legume intercropping has been widely adopted to increase crop productivity in sustainable farming systems worldwide.Among different intercropping combinations,millet and peanut intercropping can be adapted to most waterlimited areas.However,there are few studies on the differences in yield characteristics and nitrogen use efficiency between millet/peanut intercropping and monocultures under different nitrogen (N) application rates.The objective of this study was to determine the yield advantages and economic benefits,as well as the appropriate N application rate,of millet/peanut intercropping.A two-yearfield experiment was conducted with three cropping patterns (monoculture millet,monoculture peanut and millet/peanut intercropping) and four N rates (0,75,150 and 225 kg ha^(-1)).The results showed that the land equivalent ratio (LER) and net effect (NE) of the intercropping system reached their highest levels at the N input of 150 kg ha^(-1)in 2018 and 2019 (1.04 for LER,0.347 Mg ha^(-1)for NE,averaged across two years).Millet was the dominant crop in the intercropping system (aggressivity of millet and peanut (Amp)>0,competitive ratio of millet and peanut (CRmp)>1),and millet yields achieved their highest values at N inputs of 225 kg ha^(-1)for monoculture and 150 kg ha^(-1)for intercropping.NUE reached its highest levels with N inputs of 150 kg ha^(-1)for all planting patterns over the two years.Intercropping combined with an N input of 150 kg ha^(-1)achieved the highest net income of 2 791 USD ha^(-1),with a benefit-cost ratio of 1.56,averaged over the two years.From the perspective of economics and agricultural sustainable development,millet/peanut intercropping at 150 kg N ha^(-1)seems to be a promising alternative to millet or peanut monoculture.

Effects of Spatial Row Arrangement and Time of Planting Intercrops on Performance of Groundnut (Arachis hypogaea L.) under Maize (Zea mays L.)—Groundnut Intercropping System in Ejura

In monoculture, crop failure due to biotic or abiotic causes can result in partial or total output failure. The yield, socio-economic, and environmental effects of intercropping on the farmer and the environment as a whole have not received much attention. There is a dearth of knowledge on the productivity of maize-groundnut intercrops in Ghana regarding the relative timing of planting and spatial arrangement of component crops. Therefore, the objective of the study was to determine the effects of spatial row arrangement and the time of planting intercrops on the productivity of groundnut under maize-groundnut intercropping. The 5 × 3 factorial field experiment was undertaken at the Miminaso community in the Ejura-Sekyedumase municipality of the Ashanti Region of Ghana during the 2020 cropping seasons. Treatments were evaluated in a Randomized Complete Block Design (RCBD) with three replicates. The levels of row arrangement of intercrops were: one row of maize and one row of groundnut (1M1G), one row of maize and two rows of groundnut (1M2G), two rows of maize and one row of groundnut (2M1G), two rows of maize and two rows of groundnut (2M2G), sole maize and sole groundnut (M/G). The levels of time of introducing groundnut included simultaneous planting of intercrops (0 WAP), planting groundnut one week after planting maize (1 WAP) and planting groundnut two weeks after planting maize (2 WAP). There were significant (P 0.05) treatment interactions for pod and seed yields of groundnut throughout the study. The highest groundnut pod yields of 1815.00 kg/ha and 2359.00 kg/ha were recorded by the 0WAP × 1M2G treatment in the major and minor seasons of 2020, respectively, while the highest groundnut seed yields of 741.00 kg/ha and 726.00 kg/ha were recorded in the major and minor rainy seasons of 2020 by 1WAP × G and 0WAP × G treatments, respectively. The highest seed yields of groundnut (404 kg/ha and 637 kg/ha for major and minor rainy seasons, respectively) were produced by 1WAP × 2M2G.

Effect of Dandelion(Taraxacum mongolicum Hand.-Mazz.)Intercropping with Different Plant Spacing on Blight and Growth of Pepper(Capsicum annuum L.)

Intercropping of crops that can secrete bacteriostatic active substances can not only inhibit the occurrence of disease but also have an important effect on plant growth.However,the effects of dandelion intercropping on pepper blight control and pepper growth remain unclear.In this study,the control effect of dandelion on pepper blight was studied by inoculating the pepper leaves with Phytophthora infestans,and it also discusses the correlation of the occurrence of pepper epidemic disease with the pepper canopy environment,soil environment,pepper photo-synthesis,and yield index.The results showed that best plant distance for dandelion intercropping was 20 cm(P20),and the control effect reached 43.31%.As compared to the CK,SOD enzyme,POD enzyme,and PAL enzyme were significantly up-regulated during the growth of pepper;chlorophyll content in pepper leaves was significantly increased;photosynthetic characteristics were significantly increased;stem diameter and yield of crop pepper were effectively improved;and the quality of the pepper product was better,but intercropping dandelion resulted in a significant decrease of nutrients in the soil environment of pepper,so a reasonable intercropping distance was needed.The correlation analysis shows that the incidence of pepper blight(A)was significantly positively correlated with soil temperature(Q),intercellular carbon dioxide(L),and canopy air temperature(O).The incidence of capsicum blight(A)was significantly negatively correlated with chlorophyll content(F),net photo-synthetic rate(K),stomatal conductance(M),ww rate(N),soil sucrase activity(W),vitamin C(AB),and leaf PAL enzyme(J).Finally,it was deduced that intercropping dandelion could effectively control the occurrence of pepper blight while also demonstrating a complex interaction with the pepper growing environment.

Effects of Sweet Potato Rotation and Intercropping on the Microbial Community of Rhizosphere Soil

To reveal the response mechanism of soil microbial community in different planting systems of sweet potato,the effects of rotation and intercropping on microbial community structure and carbon source utilization capacities of sweet potato rhizosphere soil were studied by using phospholipid fatty acid(PLFA)and ecological board(BIOLOG ECO)through field positioning experiments.In this study,three treatments were sweet potato continuous cropping,sweet potato-wheat rotation,and sweet potato-corn intercropping.The main results showed that compared with the sweet potato continuous cropping treatment,sweet potato rotation and intercropping changed the PLFA biomass of soil microorganisms;the contents of bacteria increased by 21.82%and 38.77%,respectively(P<0.05);the contents of actinomycetes increased by 6.98%and 12.77%,and the biomass of Gram-positive bacteria increased by 28.60%and 63.44%,respectively;and the biomass of Gram-negative bacteria increased by 18.21%and 22.29%,and the fungal contents decreased by 16.60%and 13.03%,respectively.With the extension of culture time,the average well color development(AWCD value)of sweet potato-corn intercropping was significantly higher than other two treatments.The utilization capacities of carboxylic acid compounds,polymers,carbohydrates,amino acids,and amines in the sweet potato-corn intercropping treatment were significantly increased by 17.28%,14.67%,54.17%,36.62%,and 20.00%,respectively,compared with the sweet potato continuous cropping treatment.The results of the multivariate analysis(RDA)showed that the changes of soil microbial community structure and functional diversity were controlled by many factors,and the soil available potassium and total nitrogen were the main driving factors.However,sweet potato-wheat rotation and sweet potato-corn intercropping could optimize the soil microbial community structure and enhance the microbial functional diversity,and the effect of sweet potato-corn intercropping treatment was better.

Cassava Groundnut Intercropping: A Sustainable Land Management Practice for Increasing Crop Productivity and Organic Carbon Stock on Smallholder Farms

Cassava-groundnut intercropping is not a common practice among smallholder farmers in Sierra Leone even though both crops are well suited for intercropping. On-farm trials were conducted in three locations (Bai Largor, Bassah, and Njala Kanima) in the Moyamba district during the 2021 cropping season to investigate the efficacy of cassava-groundnut intercropping for increasing crop productivity and soil organic carbon stock on smallholder farms in the Moyamba district, Southern Sierra Leone. The experimental design was a randomized complete block design in three replications with treatments of sole groundnut, sole cassava and cassava-groundnut intercropping. Data on the yield and yield components of cassava and groundnut were analysed using the PROC MIXED procedure of SAS 9.4 and means were compared using the standard error of difference (SED). The above-ground biomass, number of roots per plant, and fresh root yield of cassava were not significantly (p > 0.05) affected by the cassava-based cropping system. Averaged across locations, intercropping cassava with groundnut decreased the above-ground biomass, the number of roots per plant, and fresh root yield of cassava by 17%, 11%, and 17%, respectively. The above-ground biomass, number of pods per plant and fresh pod yield of groundnut were significantly (p 1), the highest net revenue and benefit-cost ratio. The benefit-cost ratio was also favourable for the sole cassava (BCR > 1) but not favourable for the sole groundnut (BCR < 1). Averaged across locations, intercropping cassava with groundnut increased the benefit-cost ratio by 121% and 13% when compared to the sole groundnut and sole cassava. In the event of a 40% yield loss for the cassava and groundnut, the benefit-cost ratio was favourable (1.12) only for the cassava groundnut intercropping system. The net soil organic carbon stock was favourable only for the cassava-groundnut intercrop. Averaged across locations, the net soil organic carbon for the cassava-groundnut intercropping increased by 3.4% when compared to the baseline within one cropping cycle of the cassava (12 months). The results confirm that cassava-groundnut intercropping is a sustainable land management practice that could enhance crop productivity and soil organic carbon stock on smallholder farms.

Performance of Maize (Zea mays L.) and Land Equivalent Ratio under Maize-Groundnut (Arachis hypogea L.) Intercropping System

Soil fertility continues to decline in Ghana due to unsustainable human activities like bush burning, quarrying, improper farming practices, among others. To resolve this challenge, crop farmers resort to continuous use of mineral fertilizers in Ghana, which contaminates the environment and makes crop farming less sustainable and productive. One of the strategies to improve soil fertility and productivity for sustainable crop yields is intercropping. Studies were, therefore, undertaken at Miminaso in the Ejura-Sekyedumase municipality of Ashanti Region of Ghana during the 2020 cropping seasons to determine the effects of spatial row arrangement and time of planting maize and groundnut intercrops on productivity of maize and land equivalent ratio (LER). One row of maize and one row of groundnut (1M1G), one row of maize and two rows of groundnut (1M2G), two rows of maize and one row of groundnut (2M1G), two rows of maize and two rows of groundnut (2M2G), sole maize (M) and sole groundnut (G) were factorially arranged with concurrent planting of intercrops (0 WAP), planting groundnut one week after planting maize (1 WAP) and planting groundnut two weeks after planting maize (2 WAP) in a Randomized Complete Block Design with three replicates. There were significant treatment interaction (P < 0.05) effects for shelling percentage for maize in both seasons of the trial. In the major season of 2020, the highest shelling percentage of 79.30% was associated with 0 WAP × M, while in the minor season of 2020, the highest shelling percentage of 75.02% was recorded by 0 WAP × 2M1G. The treatment interaction effects for maize grain yield were significant only in the minor season of 2020 with the highest maize grain yield of 6341 kg/ha being produced by the sole maize treatment, followed by 1 WAP × 2M2G (6152 kg/ha). The highest LER of 3.05 was associated with 1 WAP × 2M2G in the minor season of 2020. Planting groundnuts within the first week of planting maize (1 WAP) increased maize seed yield and LER in two rows of maize and two rows of groundnut (2M2G) row arrangements.

Evaluation of the Productivity of Intercropping Plantain Cultivar (PITA 3) Fertilized with Two Types of Manure, under Coconut Tree Based (Cocos nucifera L.), on the Tertiary Sands of Côte d’Ivoire

Pressure on land tenure is having a negative impact on the coconut sector, reducing farmers’ incomes. Intercropping cultivars plantain under coconut based has been considered as a solution to this problem. The aim of this work is to diversify the sources of income for coconut growers. The plantain variety PITA 3, popularised by the CNRA, was grown in coconut inter-rows (PB113+), with two types of manure (chemical, organic). Six (06) treatments D1, D2, D3, D4, D5 and D6 were studied. In the tenth month after planting, treatment D3, which included banana plants fertilised with 9 kg of manure/plant, got the best agromorphological performance: height (264.08 cm), neck circumference (57.68 cm) and 12 leaves. In terms of production parameters, D3 banana plants had a shorter production cycle (347 days) and the highest diet mass (9.3 kg). However, the plants that received no fertiliser (D6) showed stunted growth and were unable to produce brunch. The fertilization of plantain with 10 t/ha of laying hen droppings permitted good development and production of plantains on tertiary sands.

Profitability Level and Determinants of Tea Intercropping in Taraba State

Intercropping involves the cultivation of more than one crop on a plot of land at a particular time.Tea intercropping with other crops can increase the profitability of farmers and the development of tea plants.The study estimated the profitability level of intercropped tea farms and determined the factors affecting the profitability of tea intercropping systems in the study area.Information was obtained from two hundred and four tea farmers using a well-structured questionnaire.The analytical techniques used in the study were descriptive analysis and linear regression.The results revealed that the majority(95.6%)of the farmers are from Kakara and Nyiwa towns.There are few(2.9%)women involved in tea farming in Taraba State.29%of the tea farmers are young less than 30 years and old above 60 years.Fifteen percent of the farmers are single,83.8%are married and 1.5%are divorced.About 40%of the tea farmers had no formal education,21%have between 1-6 years of education,19%had 7-12 years of education and 21%had greater than 12 years of education.The gross margin is N289,900,581.9 and the gross margin per farmer is N1,421,081.28.The net income is N2,879,055,533.3 and the net income per farmer is N1,411,301.63.The amount of profit tea farmers make in Taraba State is N1,425,001 and the profit per farmer is N6,985.30.Labour costs(weeding,pruning,application of insecticide,watering)and cost of materials(cutlass,file,chemical,bag and others)are significant determinants of the profit level of the tea intercropping system in Taraba State.Tea intercropping farming is profitable in Taraba State Nigeria.

Impacts of soil fertility management on productivity and economics of rice and fodder intercropping systems under rainfed conditions in Odisha,India

Under small and marginal farm conditions,allocation of land exclusively for forages is not possible.Hence,integration of forages in existing crop geometry can ensure production of grain and fodder,simultaneously under rainfed conditions.Afield experiment was conducted to study the effect of different nutrient management practices on rice and fodder intercropping systems under rainfed conditions during 2015-2017.The intercropping system comprised(i)sole rice(R),(ii)rice and cowpea(5:2)(CP)and(iii)rice and ricebean(5:2)(RB)whereas the different nutrient management practices comprised(i)application of farm yard manure(FYM)at 5t ha^(-1)(farmers'practice)(N_(1)),(ii)application of inorganic fertilizer(recommended dose of fertilizer(RDF)of rice,60:30:30 kg ha^(-1) of N:P_(2)O_(5):K_(2)O)(N_(2))and(iii)application of both FYM at 5t ha^(-1) and 50%of RDF inorganic fertilizer(N3).The results of the experiment revealed that the growth attribute such as leaf area was influenced significantly when fodder crops were taken as intercrops because rice plant was getting more nitrogen from soil due to nitrogen fixation of leguminous fodder crops.Among the nutrient management practices,significant differences in leaf area were found beween N2 and and between N_(3)and N_(1)treatments.However,regarding total number of effective tillers,significant differences were found neither between nutrient management practices nor between cropping systems.The rice equivalent yield(REY)based on price(REY_(P))was found to be significantly lower in CP(2615 kg ha^(-1);-6.4%)and RB intercropping systems(2571 kg ha^(-1);-8.0%)than in R monocropping system(2794 kg ha^(-1)).However,the REY based on energy(REY_(E))of CP(2999 kg ha^(-1);+7.3%)and RB(2960 kg ha^(-1);+5.9%)were found to be significantly higher than that of R(2794 kg ha^(-1))irrespective of nutrient management practices.Between different nutrient management practices,the N3 treatment recorded the highest REY_(P)and REY_(E)which was at par with the N_(2)treatment and significantly higher than the N1 treatment irrespective of cropping systems.The combined application of both organic and inorganic sources of nutrients helped to supply nutrients throughout the growing season,which led to improved growth parameters and rice yield.The R monocropping system resulted in more income and rain water use efficiency(RWUE)closely followed by rice and fodder intercropping systems.However,the REYe and energy use efficiency(EUE)of rice and fodder intercropping systems were higher than those of R.Also,fodder helped to meet the requirement of cattle feeding in the off-season.Hence,the intercropping system is advocated in the study zone.Further study can be done on ecosystem services and carbon sequestration potential of the intercropping system,as well as the system's coping ability in response to short drought through observing periodic soil moisture regime in root zone.

The importance of aboveground and belowground interspecific interactions in determining crop growth and advantages of peanut/maize intercropping

Intercropping of maize(Zea mays L.) and peanut(Arachis hypogaea L.) often results in greater yields than the respective sole crops. However, there is limited knowledge of aboveground and belowground interspecific interactions between maize and peanut in field. A two-year field experiment was conducted to investigate the effects of interspecific interactions on plant growth and grain yield for a peanut/maize intercropping system under different nitrogen(N) and phosphorus(P) levels. The method of root separation was employed to differentiate belowground from aboveground interspecific interactions. We observed that the global interspecific interaction effect on the shoot biomass of the intercropping system decreased with the coexistence period, and belowground interaction contributed more than aboveground interaction to advantages of the intercropping in terms of shoot biomass and grain yield. There was a positive effect from aboveground and belowground interspecific interactions on crop plant growth in the intercropping system, except that aboveground interaction had a negative effect on peanut during the late coexistence period. The advantage of intercropping on grain came mainly from increased maize yield(means 95%) due to aboveground interspecific competition for light and belowground interaction(61%–72% vs. 28%–39% in fertilizer treatments). There was a negative effect on grain yield from aboveground interaction for peanut, but belowground interspecific interaction positively affected peanut grain yield.The supply of N, P, or N + P increased grain yield of intercropped maize and the contribution from aboveground interspecific interaction. Our study suggests that the advantages of peanut/maize intercropping for yield mainly comes from aboveground interspecific competition for maize and belowground interspecific facilitation for peanut, and their respective yield can be enhanced by N and P. These findings are important for managing the intercropping system and optimizing the benefits from using this system.

Maize-soybean strip intercropping： Achieved a balance between high productivity and sustainability

Intercropping is one of the most vital practice to improve land utilization rate in China that has limited arable land resource. However, the traditional intercropping systems have many disadvantages including illogical field lay-out of crops, low economic value, and labor deficiency, which cannot balance the crop production and agricultural sustainability. In view of this, we developed a novel soybean strip intercropping model using maize as the partner, the regular maize-soybean strip intercropping mainly popularized in northern China and maize-soybean relay-strip intercropping principally extended in southwestern China. Compared to the traditional maize-soybean intercropping systems, the main innovation of field lay-out style in our present intercropping systems is that the distance of two adjacent maize rows are shrunk as a narrow strip, and a strip called wide strip between two adjacent narrow strips is expanded reserving for the growth of two or three rows of soybean plants. The distance between outer rows of maize and soybean strips are expanded enough for light use efficiency improvement and tractors working in the soybean strips. Importantly, optimal cultivar screening and increase of plant density achieved a high yield of both the two crops in the intercropping systems and increased land equivalent ratio as high as 2.2. Annually alternative rotation of the adjacent maize-and soybean-strips increased the grain yield of next seasonal maize, improved the absorption of nitrogen, phosphorus, and potasium of maize, while prevented the continuous cropping obstacles. Extra soybean production was obtained without affecting maize yield in our strip intercropping systems, which balanced the high crop production and agricultural sustainability.

Effects of maize-soybean relay intercropping on crop nutrient uptake and soil bacterial community

Maize-soybean relay intercropping is an effective approach to improve the crop yield and nutrient use efficiency,which is widely practiced by farmers in southwest of China.To elucidate the characteristics of different planting patterns on crop nutrient uptake,soil chemical properties,and soil bacteria community in maize-soybean relay intercropping systems,we conducted a field experiment in 2015–2016 with single factor treatments,including monoculture maize(MM),monoculture soybean(MS),maize-soybean relay intercropping(IMS),and fallow(CK).The results showed that the N uptake of maize grain increased in IMS compared with MM.Compared with MS,the yield and uptake of N,P,and K of soybean grain were increased by 25.5,24.4,9.6,and 22.4%in IMS,respectively,while the N and K uptakes in soybean straw were decreased in IMS.The soil total nitrogen,available phosphorus,and soil organic matter contents were significantly higher in IMS than those of the corresponding monocultures and CK.Moreover,the soil protease,soil urease,and soil nitrate reductase activities in IMS were higher than those of the corresponding monocultures and CK.The phyla Proteobacteria,Acidobacteria,Chloroflexi,and Actinobacteria dominated in all treatments.Shannon’s index in IMS was higher than that of the corresponding monocultures and CK.The phylum Proteobacteria proportion was positively correlated with maize soil organic matter and soybean soil total nitrogen content,respectively.These results indicated that the belowground interactions increased the crop nutrient(N and P)uptake and soil bacterial community diversity,both of which contributed to improved soil nutrient management for legume-cereal relay intercropping systems.

Nitrate Leaching from Maize Intercropping Systems with N Fertilizer Over-Dose

A 2-yr field experiment was conducted on a calcareous alluvial soil with four summer maize intercropping systems at Shangzhuang Experiment Station （116.3°E, 39.9°N） in the North China Plain. The objective was to determine nitrate leaching from intercropping systems involving maize （Zea mays L.）： sole maize （CK）, maize ＋ soybean （CST）, maize ＋ groundnut （CGT）, maize ＋ ryegrass （CHM）, and maize ＋ alfalfa （CMX）. Intercropping greatly reduced nitrate accumulation in the 100-200 cm soil layers compared with maize monoculture. Nitrate accumulation under intercropping systems decreased significantly at the 140-200 cm soil depth; the accumulation varied in the order CK〉CST〉CMX〉CHM〉CGT. However, compared to the CK treatment, nitrate leaching losses during the maize growing period were reduced by 20.9- 174.8 （CGT）, 35.2-130.8 （CHM）, 60.4-122.0 （CMX）, and 30.6-82.4 kg ha-1 （CST）. The results also suggested that intereropping is an effective way to reduce nitrogen leaching in fields with N fertilizer over-dose.

Biochemical and microbial properties of rhizospheres under maize/ peanut intercropping

Maize/peanut intercropping system shows the significant yield advantage. Soil microbes play major roles in soil nutrient cycling and were affected by intercropping plants. This experiment was carried out to evaluate the changing of rhizosphere microbial community composition, and the relationship between microbial community and soil enzymatic activities, soil nutrients in maize/peanut intercropping system under the following three treatments： maize （Zea mays L.） and peanut （Arachis hypogaea L.） were intercropped without any separation （NS）, by half separation （HS） using a nylon net （50 μm） and complete separation （CS） by using a plastic sheet, respectively. The soil microbial communities were assessed by phospholipid fatty acid （PLFA）. We found that soil available nutrients （available nitrogen （Avail N） and available phosphorus （Avail P）） and enzymatic activities （soil urase and phosphomonoesterase） in both crops were improved in NS and HS treatments as compared to CS. Both bacterial and fungal biomasses in both crops were increased in NS followed by HS. Furthermore, Gram-positive bacteria （G＋） in maize soils were significant higher in NS and HS than CS, while the Gram-negative （G-） was significant higher in peanut soil. The ratio of normal saturated to monounsaturated PLFAs was significantly higher in rhizosphere of peanut under CS treatment than in any other treatments, which is an indicator of nutrient stress. Redundancy analysis and cluster analysis of PLFA showed rhizospheric microbial community of NS and HS of both plants tended to be consistent. The urase and Avail N were higher in NS and HS of both plants and positively correlated with bacteria, fungi （F） and total PLFAs, while negatively correlated with G＋/G- and NS/MS. The findings suggest that belowground interactions in maize/peanut intercropping system play important roles in changing the soil microbial composition and the dominant microbial species, which was closely related with the improving of soil available nutrients （N and P） and enzymatic activities.

Influence of Garlic Intercropping or Active Emitted Volatiles in Releasers on Aphid and Related Beneficial in Wheat Fields in China

In order to develop biological control of aphids by a ＂push-pull＂ approach, intercropping using repellent emitting plants was developed in different crop and associated plant models. Garlic is one of the potential plant that could be inserted in crops to decrease the pest occurrence in neighboring crop plots. In this study, field works were conducted in wheat fields in Langfang Experimental Station, Hebei Province in China from October 2009 to July 2010 during wheat developmental season. The effect of wheat intercropping with garlic but also the volatiles emission on the incidence of the English grain aphid, Sitobion avenae Fabricius （Homoptera： Aphididae） was assessed. Natural beneficial occurrence and global yields in two winter wheat varieties that were susceptible or resistant to cereal aphid were also determined comparing to control plots without the use of garlic plant intercrop nor semiochemical releaser in the fields. S. avenae was found to be lower in garlic oil blend treatment （GOB）, diallyl disulfide treatment （DD） and wheat-garlic intercropping treatment （WGI） when compared to the control plots for both two varieties （P〈0.01）. Both intercropping and application of volatile chemicals emitted by garlic could improve the population densities of natural enemies of cereal aphid, including ladybeetles and mummified aphids. Ladybeetle population density in WGI, GOB and mummified aphids densities in WGI, DD were significantly higher than those in control fields for both two varieties （P〈0.05）. There were significant interactions between cultivars and treatments to the population densities of S. avenae. The 1 000-grain weight and yield of wheat were also increased compared to the control. Due to their potential alternatives as a biological control agent against cereal aphid, garlic intercropping and related emitted volatiles are expected to contribute to the further improvement of integrated pest management systems and to potentially reduce the amount of traditional synthetic pesticides applied in wheat fields.