Maize-soybean Intercropping System Research Articles

Effect of shading on accumulation of soybean isoflavonoid under maize-soybean strip intercropping systems

ABSTRACTMaize-soybean strip intercropping system is an important ecological planting system; the wide development of intercropped soybean has contributed to the soybean industry in China. Soybean growth and seed production were affected by the shading from maize. Previous studies confirmed that relay strip intercropping shading facilitates the accumulation of isoflavone glucosides but does not take advantage of the accumulation of isoflavone aglycone. However, the regulation of isoflavones accumulation under strip intercropping system was unknown; in which soybean and maize were sown at the same time, and soybean was mainly shaded in the reproductive stage. In order to reveal the effects of intercropping shading on the isoflavones accumulation in soybean seed, two independent field experiments were conducted in eastern China. We compared the isoflavones profiles of soybean seeds, which were grown under various maize-soybean intercropping systems with different shade levels. The results showed that the intercropping shading was not benefited to the accumulation of soy-isoflavones, including aglycones and isoflavones glycosides and various forms of isoflavones were decreased with the decline of photosynthetic active radiation. Multivariate statistical analysis and significance analysis showed that acylated isoflavones may be more susceptible to intercropping shading.Abbreviations: HCA: Hierarchical cluster analysis; PAR: photosynthetically active radiation; PCA: Principal component analysis; LC-MS: Liquid chromatography mass spectrometer.

Effects of phosphorus application rates and depths on P utilization and loss risk in a maize-soybean intercropping system

In order to explore the advantage of intercropping on phosphorus (P) efficient utilization and the reduction of soil P loss, a field experiment in a maize-soybean intercropping system, which included three P application (P2O5) rates (CP: 168 kg·hm-2; RP1: 135 kg·hm-2; RP2: 101 kg·hm-2) and three P application depths (D1: applied in 5 cm depth; D2: applied in 15 cm depth; D3: 1/2 of P fertilizer applied in 5 cm depth and another 1/2 in 15 cm depth) was carried out to analyze the effects of P application rates and depth on crop aboveground biomass, grain yield, crop P uptake, soil total and available P contents, and soil P adsorption-desorption characteristics. Compared with control treatment, the aboveground biomass, grain yield, crop P uptake, soil total P, and available P content were increased significantly by P application, regardless of P rate and application depth. Under the same application depth, RP1 had similar grain yield but higher crop P uptake compared with CP, and thus higher P apparent utilization efficiency. Under the same P application rate, the application depth of D2 had the highest crop aboveground biomass, grain yield, P uptake, soil total P, and available P. According to the characteristic of soil P adsorption-desorption, the treatment with the rate of RP1 and the depth of D2 had the strongest soil P retention capacity, which had advantage in alleviating P loss. These results suggested that reducing application rate but increasing application depth of P fertilizer could improve P use efficiency and reduce soil P loss without sacrifice in crop production in maize-soybean relay intercropping system.

Optimized nitrogen application methods to improve nitrogen use efficiency and nodule nitrogen fixation in a maize-soybean relay intercropping system

In China, the abuse of chemical nitrogen (N) fertilizer results in decreasing N use efficiency (NUE), wasting resources and causing serious environmental problems. Cereal-legume intercropping is widely used to enhance crop yield and improve resource use efficiency, especially in Southwest China. To optimize N utilization and increase grain yield, we conducted a two-year field experiment with single-factor randomized block designs of a maize-soybean intercropping system (IMS). Three N rates, NN (no nitrogen application), LN (lower N application: 270 kg N ha−1), and CN (conventional N application: 330 kg N ha−1), and three topdressing distances of LN (LND), e.g., 15 cm (LND1), 30 cm (LND2) and 45 cm (LND3) from maize rows were evaluated. At the beginning seed stage (R5), the leghemoglobin content and nitrogenase activity of LND3 were 1.86 mg plant−1 and 0.14 mL h−1 plant−1, and those of LND1 and LND2 were increased by 31.4 and 24.5%, 6.4 and 32.9% compared with LND3, respectively. The ureide content and N accumulation of soybean organs in LND1 and LND2 were higher than those of LND3. The N uptake, NUE and N agronomy efficiency (NAE) of IMS under CN were 308.3 kg ha−1, 28.5%, and 5.7 kg grain kg−1 N, respectively; however, those of LN were significantly increased by 12.4, 72.5, and 51.6% compared with CN, respectively. The total yield in LND1 and LND2 was increased by 12.3 and 8.3% compared with CN, respectively. Those results suggested that LN with distances of 15–30 cm from the topdressing strip to the maize row was optimal in maize-soybean intercropping. Lower N input with an optimized fertilization location for IMS increased N fixation and N use efficiency without decreasing grain yield.

MAIZE–SOYBEAN INTERCROPPING FOR SUSTAINABLE INTENSIFICATION OF CEREAL–LEGUME CROPPING SYSTEMS IN NORTHERN NIGERIA

SUMMARYField studies were conducted during the 2014 and 2015 wet seasons at Zaria in the northern Guinea savanna and at Iburu in the southern Guinea savanna of Nigeria to determine the productivity of maize–soybean intercropping system. There were four treatment combinations in the experiment: sole maize; sole soybean; maize spaced at 50 cm and intercropped with soybean; and maize spaced at 65 cm and intercropped with soybean. The experiment was laid out in a randomized complete block design with three replications. The results showed that sole cropped maize and soybean generally outperformed the intercropped component crops. Land Equivalent Ratio (LER) was greater than 1 for all the intercrop treatments, indicating that it is advantageous to grow maize and soybean in association than in pure stands. Except for 2014 in Zaria, LER for intercropped maize spaced at 50 cm was higher than that for maize spaced at 65 cm. Gross Monetary Value (GMV) was generally higher for intercrops than sole crops except in Iburu in 2015 where GMV for intercropped maize spaced at 65 cm was similar to those of sole maize and soybean. Monetary Advantage Index (MAI) was positive for all intercrop treatments in both locations and years, which shows definite yield and economic advantages compared to the sole cropping systems. This suggests that farmers can intercrop soybean and maize with maize spaced at 50 cm and 65 cm.

Photosynthetic Response of Soybean Leaf to Wide Light-Fluctuation in Maize-Soybean Intercropping System.

In maize-soybean intercropping system, soybean plants will be affected by the wide light-fluctuation, which resulted from the shading by maize plants, as the shading of maize the light is not enough for soybean in the early morning and late afternoon, but at noon, the light is strong as the maize shading disappeared. The objective of this study is to evaluate the photosynthetic response of soybean leaf to the wide light-fluctuation. The data of diurnal variation of photosynthetic characters showed that the photosynthetic rate of intercropped soybean was weaker than that of monocropped soybean. The chlorophyll content, ratio of chlorophyll a/b, and AQE (apparent quantum efficiency) were increased and Rd (dark respiration rate) was decreased for the more efficient interception and absorption of light and carbon gain in intercropping. δRo (The efficiency/probability with which an electron from the intersystem electron carriers was transferred to reduce end electron acceptors at the PSI acceptor side) and φRo (the quantum yield for the reduction of the end electron acceptors at the PSI acceptor side) in intercropped soybean leaf were lower compared to those in monocropped one, which showed that the acceptor side of PSI might be inhibited, and also it was the main reason that soybean plants showed a low photosynthetic capacity in intercropping. ψEo (the efficiency/probability with an electron moves further than QA-) in monocropping and intercropping decreased 5.8, and 35.7%, respectively, while φEo (quantum yield for electron transport) decreased 27.7 and 45.3% under the high radiation at noon, which suggested that the acceptor side of PSII was inhibited, while the NPQ became higher. These were beneficial to dissipate excess excitation energy in time, and protect the photosynthetic apparatus against photo-damage. The higher performance index on the absorption basis (PIABS) and lower δRo, φRo, ψEo, and φEo of intercropped soybeans compared to monocropping under high radiation indicated that the electron transfer of intercropped soybean was inhibited more seriously and intercropped soybean adjusted the electron transport between PSII to PSI to adapt the light-fluctuation. Higher NPQ capacity of intercropped soybeans played a key role in keeping the leaf with a better physiological flexibility under the high radiation.

Response of leaf morphology and photosynthetic characteristics of soybean in maize-soybean relay strip intercropping system

Response of leaf morphology and photosynthetic characteristics of soybean in maize-soybean relay strip intercropping system

Changes in light environment, morphology, growth and yield of soybean in maize-soybean intercropping systems

The maize-soybean intercropping system has become increasingly popular in many areas of the world, particularly in China, due to its high productivity and the harvest of two different grains. While efforts have been made to maintain the yield of the taller maize crop, there is limited understanding of how the morphology, growth and yield of the lower soybean crop changes in response to the shading by maize. We therefore conducted a three-year field experiment from 2013 to 2015 to investigate the changes in light environment, growth of individual organs, biomass, and grain yield of soybean under two intercropping patterns (1M1S, one row of maize with one row of soybean; 2M2S, two rows of maize with two rows of soybean) as compared to monoculture. Our results showed that at soybean flowering stage, the R:FR ratio at the top of soybean canopy was reduced 17–21% more than the photosynthetically active radiation (PAR) under intercropping compared to monoculture, with 15–19% more reduction under 1M1S than 2M2S. This led to increased internode lengths, plant height and specific leaf area (SLA), but reduced branching of soybean plants under intercropping. These morphological changes enabled the crop to intercept relatively more light and the shading also increased the light use efficiency (LUE) of soybean. However, these positive responses were not able to compensate the effect of reduced leaf area (due to smaller leaf size and less branching) and total light interception, leading to reduced biomass and grain. The reduction in grain yield was mainly caused by the reduced number of grains (particularly on the middle nodes) produced by the intercropped soybean plants, while the grain size remained unchanged. The data and results of this study may be used to develop and parameterize crop models for simulating development and growth of soybean crop in response to changes in the light environment under intercropping.

Effects of N application reduction and fertilizing distance on saving fertilizer and improving yield in maize/soybean intercropping system

To study the effect of N supplied levels and fertilization distances on saving fertilizer and improving yield in maize/soybean intercropping system, a field experiment was carried out with three N supplying levels ( RN1: 210 kg N·hm-2, RN2: 270 kg N·hm-2 and CN: 330 kg N·hm-2) and four fertilizing distances (D1: 0 cm, D2: 15 cm, D3: 30 cm and D4: 45 cm, indicating the distance between fertilizing site and maize in narrow row). Compared with CN, the results showed that dry matter accumulation and translocation, and their contribution to grain of post-anthesis maize under RN2 were increased by 1.4%, 23.0% and 16.0%, respectively. Meanwhile, kernel number per ear and grain yield per plant of maize were increased by 1.6% and 4.9%. For soybean, dry matter accumulation and translocation, and their contribution to grain at pre-anthesis under RN2 were increased by 2.1%, 37.9% and 26.9%, respectively. Both of soybean grain number and yield per plant were increased by 7.3%. For the maize-soybean intercropping system, N uptake and use efficiency of RN2 were 5.0% and 44.4% higher than those of CN. The soil N content of maize was raised by 4.1% under RN2, but decreased by 0.8% for soybean. The saving fertilizer and improving yield effect of D2 were the best among all the fertilizing distances. Under RN2, contribution rate of dry matter accumulation to grain after anthesis and kernel number per ear of maize in D2 were 57.2% and 9.4% higher than those of D1. Compared with D4, the contribution rate of dry matter accumulation to grain before anthesis and grain number per plant of soybean in D2 were increased by 335.2% and 2.4%, respectively. For the maize/soybean intercropping system, N uptake and use efficiency of D2 were 15.1% and 112.4% greater than those of D1, and 21.4% and 66.3% higher than those of D4. The total soil N content of maize in D2 was 6.6% higher than that of D1, and the index for soybean was 16.0% higher than that of D4. Appropriate N application reduction and fertilizing distance would be beneficial to transfer dry matter to grain, improve grain number per plant, 100-grain mass and yield, promote N uptake and increase fertilizer use efficiency in the intercropping system, which could achieve the purpose of saving fertilizer and improving yield.

Relationship between cellulose accumulation and lodging resistance in the stem of relay intercropped soybean [Glycine max (L.) Merr.

Stem lodging is the most important constraint for soybean at seedling stage in maize–soybean intercropping in China. This study was conducted to determine whether cellulose accumulation and lodging resistance of soybean was affected by different cropping systems and soybean varieties with different shading tolerance at seedling stage. Three soybean varieties – Nandou 032-4 (shade susceptible), Jiuyuehuang (moderately shade tolerant) and Nandou 12 (shade tolerant) – were used to investigate the effect of intercropping on soybean lodging behavior and cellulose accumulation in stems and its relationship to lodging resistance. Shading by maize significantly reduced cellulose accumulation and the stem breaking strength of the soybean, which were significantly negatively correlated with the lodging rate. In the maize–soybean intercropping system, shading inhibited sucrose transportation and degradation into cellulose in the soybean stem. Less content of cellulose in soybean stem at the seedling stage resulted in lodging in the intercropping system. Compared with shade susceptible varieties, Nandou 12 had higher cellulose accumulation and related enzyme activities in the stem, and thus the stem breaking strength and lodging resistance of the basal stem increased. The higher activities of sucrose phosphate synthase and sucrose synthetase in the stem were associated with shade tolerance and lodging resistance. Thus, we concluded that the high physical strength and high cellulose contents of the stem of shade tolerant soybean reduced the rate of lodging in the maize–soybean intercropping system.

WATER USE EFFICIENCY AND WATER DISTRIBUTION RESPONSE TO DIFFERENT PLANTING PATTERNS IN MAIZE–SOYBEAN RELAY STRIP INTERCROPPING SYSTEMS

SUMMARYUnderstanding crop water use in mixed crops over sole cropping is vital for developing optimum water management systems for crop production. In this study, a two-year field experiment with typical maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] relay strip intercropping (2:2 maize-to-soybean rows; 200 cm bandwidth) was carried out in the 2013 and 2014 growing seasons. The quantitative effects of various planting patterns on the water-use efficiency (WUE) and water distribution were investigated. Our results indicated that soil volumetric water content and soil evaporation in the intercropping systems showed decreasing trends in the order: maize row (MM) < maize-to-soybean row (MS) < soybean row (SS). The highest leaf transpiration (1.91 and 2.07 mmol m−2 s−1) for the intercropped maize was measured in each of the two years in the 20 cm maize narrow-row planting pattern and decreased thereafter. Opposite trend was observed for the intercropped soybean; the highest soybean leaf transpiration (7.01 and 6.80 mmol m−2 s−1 for 2013 and 2014, respectively) was recorded in the 70 cm. The WUE of maize and soybean intercrops was lower than that of sole crop counterparts. However, the maximum group water use efficiency (GWUE) of 26.08 and 26.20 kg ha−1 mm−1 in the 40–50 cm maize narrow-row planting pattern was, respectively, 39.6% and 23% higher compared with that of sole crops. The water equivalent ratio (WER) values ranged from 1.60–1.79, suggesting better crop water use in the intercrops over sole cropping. Planting patterns provided by 40–50 cm maize narrow-row spacing were considered the most efficient in terms of maximum total yields, GWUE and WER. These results suggest that an appropriate reduction in the spacing of narrow maize row with wide soybean row could be an efficient crop management method to achieve optimal WUE and homogeneous water distribution in maize–soybean intercropping systems.

Variation of combination yield of maize and soybean under the maize-soybean inter-cropping system in Sichuan Province

Variation of combination yield of maize and soybean under the maize-soybean inter-cropping system in Sichuan Province

减量施氮对玉米-大豆套作系统下作物氮素吸收和利用效率的影响

减量施氮对玉米-大豆套作系统下作物氮素吸收和利用效率的影响

Effect of the maize–soybean intercropping system on the potential bioavailability of magnesium, iron and zinc

This study concerned the effect of different intercropping systems (alternating rows and alternating strips) of maize and soybean compared with single cropping, in combination with different fertilisers (biofertiliser, organic fertiliser, and urea) on the potential availability of magnesium (Mg), iron (Fe) and zinc (Zn) from grain, through their ratio with phytate (as inhibitor) and β-carotene (as promoter). The higher grain yield and land equivalent ratio obtained under alternating rows + biofertiliser treatment demonstrated the improved ability of crops in close proximity for better utilisation of existing agro-ecological conditions. Alternating rows + organic fertiliser decreased the molar ratios phytate : β-carotene, phytate : Fe, phytate : Mg and phytate : Zn, indicating increased availability of the mineral elements in both crops. However, alternating strips + organic fertiliser contributed mostly to an increase in β-carotene, Mg, Fe and Zn concentrations in soybean. Increased grain yield of both crops was followed by decrease in β-carotene and increase in phytate, particularly in maize. In soybean, β-carotene could be considered as the main contributor to Fe availability. Accordingly, cropping in alternating rows or strips, combined with biofertilisers, could serve as fortification measures for improved nutritional quality of maize and soybean grain, without grain yield losses.

Performance of Maize-Soybean Intercropping under Various N Application Rates and Soil Moisture Conditions in Northern Mozambique

Soybean has attracted increasing attention as a cash crop while subsistent maize production is the first priority for smallholder farmers in southern Africa. Our study examined the performance of maize-soybean intercropping system at three sites across northern Mozambique. Both monocropped and intercropped maize received three levels of N application, while soybean was grown without additional fertilization. The grain yield of monocropped maize applied N at three rates and that of monocropped soybean ranged 1.6 – 2.1 t ha–1 and 0.57 t ha–1, respectively, in Nampula; 1.7 – 3.9 t ha–1 and 1.87 t ha–1, respectively, in Gurue; and 2.8 – 4.5 t ha–1 and 2.01 t ha–1, respectively, in Lichinga. Relative to these values, maize-soybean intercropping demonstrated advantageous productivity over monocropping in terms of the land equivalent ratio (LER) at 1.15 – 1.49 across the experimental sites. LER above 1 was mainly attributed to the consistently superior growth of intercropped maize than the monocropped maize. Under moist field conditions, the LER values were particularly high in the non-fertilized plots because maize plants became more competitive and depressed the intercropped soybean yields to greater degrees with increasing N application rates. When exposed to a dry spell, intercropped soybean showed an apparent benefit in drought avoidance, as shown by the slow depletion of the soil water potential and leaf stomatal conductance and by the retention of the aboveground biomass relative to the monocropped soybean. These results indicate that maize-soybean intercropping can be beneficial to introduce soybean while ensuring subsistent maize production in the low-N-input and drought-prone environment that prevails in the region.

English

The present study was carried out to evaluate the productivity of maize soybean intercropping system and to identify the best combination that maximizes productivity of the system. Maize hybrid (BH540) at 44,444 plants ha -1 and three soybean varieties (AFGAT, Awassa-95 and Crawford) in a factorial combination of three planting densities (25%, 50% and 75%) of the recommended population density of soybean with the respective sole of each variety of component crops were arranged in a randomized complete block design with three replications. Sole cropped maize grain yield (3189.80 kg ha -1 ) was non-significantly greater than intercropped (2753.70 kg ha -

English

The adoption of ISFM technologies such as maize-soybean intercropping system is being promoted as one of the options to address low soil fertility and crop productivity among the farmers of the central highland of Kenya. The purpose of this study was therefore to determine the effects of maize-soybean intercropping patterns on soil inorganic N, N uptake and soil chemical properties. The experiment conducted during 2012 LR and 2012 SR and it was arranged in a randomized complete block design (RCBD) with four replications. The treatments were four maize (M) – soybean (S) intercropping patterns (conventional=1M:1S; MBILI-MBILI=2M:2S; 2M:4S; 2M:6S) and two sole crops of maize and soybean, respectively. The results showed that at Embu during 2012 LR, at harvest the MBILI and 2M:4S treatments observed significantly (p=0.0525) the lowest N03- - N content (8.24 mg kg-1 and 9.15 mg kg-1, respectively); and at Kamujine during the same 2012 LR, at harvest the sole soybean treatment recorded statistically (p = 0.0301) the highest N03- - N content (8.24 mg kg-1). At Kamujine the sole soybean treatment recorded statistically (p=0.0131) the highest (12.84 mg kg-1) soil mineral N. The N uptake by maize and soybean was significantly affected by the intercropping patterns and it was positively correlated with soil mineral N, at both sites during the sampling period. During 2012 SR at Embu site, the MBILI treatment observed significantly the highest soil total N value of 0.05% (p=0.0530). The soil SOC was not significantly affected by the intercropping patterns at this location. The SOC was significantly affected by the intercropping and the conventional treatment recorded the highest value of 2.46%, p=0.0020.       Key words: Maize-soybean, intercropping patterns, soil mineral-N, N-uptake, chemical soil properties, central highlands, Kenya.

Effects of different maize (Zea mays L.) - soybean (Glycine max (L.) Merrill) intercropping patterns on yields and land equivalent ratio

In central highlands of Kenya, the low soil fertility and inability to replenish it are amongst the major constraints affecting the productivity of maize and cash crops, leading to hunger and poverty. The adoption of ISFM technologies such as maize-soybean intercropping system is being promoted as one of the options to address low crop productivity among the farmers. This study intended to determine the effects of maize-soybean intercropping patterns on yields and to quantify the land equivalent ratio (LER) of different maize–soybean intercropping patterns in the two contrasting sites. The experiment was arranged in a randomized complete block design (RCBD) with four replications. The treatments were four maize (M) – soybean (S) intercropping patterns (conventional=1M:1S; MBILI-MBILI=2M:2S; 2M:4S; 2M:6S) and two sole crops of maize and soybean, respectively. The results showed that in both sites during the both seasons maize stover and grain yields were significantly affected by the intercropping pattern. During 2012 LR at Embu site the MBILI treatment produced significantly higher stover and grain yields (13.12 t ha-1, p=0.0001 and 6.11 t ha-1, p<0.0001, respectively) than all other treatments. During 2012 SR, still the MBILI treatment had recorded significantly the highest stover and grain yield (7.62 t ha-1, p<0.0001 and 5.62 t ha-1 p=0.0467, respectively) than all other treatments. During 2012 LR at Kamujine site the conventional treatment produced significantly the highest stover yield (3.87 t ha-1, p=0.0461) than only the 2M:6S treatment. During 2012 SR at Kamujine site, the MBILI treatment had recorded significantly the highest stover and grain yield (6.55 t ha-1, p=0.0005 and 3.55 t ha-1 p=0.0006, respectively) than all other treatments. During both seasons in both sites, the soybean yield was significantly affected by the intercropping pattern. During the 2012 LR, the yields were reduced by 60 and 81% due to the intercropping with maize, at Embu and Kamujine, respectively; whereas, during the 2012 SR, the yields were reduced by 52 and 78% as effect of intercropping with maize, at Embu and Kamujine, respectively. During both seasons at both locations, the partial land equivalent ratio (LER) values were significantly affected by the intercropping patterns (p<0.0001). Key words: Maize-soybean yields, land equivalent ratio, intercropping patterns, central highlands, Kenya.

Assessing the Effects of Integrated Soil Fertility Management on Biological Efficiency and Economic Advantages of Intercropped Maize (Zea Mays L.) and Soybean (Glycine Max L.) in DR Congo

Interactions among species play an important role in determining the structure and the dynamics of plant communities. The main objectives of the study were (i) to assess and compare different competition indices and their relationship with yield component under different inorganic and organic fertilizers regimes; and (ii), to identify nutrient management regimes options that lead to high yields and incomes in a maize-soybean intercropping system. Effects of integrated soil practices management on crop competition, yields components and economics advantage in maize-soybean intercropping system in a savannah region of the DR-Congo were investigated. Field trials were conducted at two sites in a randomized complete block design with six treatments replicated four times. Grain yield and yield components increased under integrated soil fertility management (ISFM) (inorganic or mineral and organic fertilization combined) than other treatments at

间作对玉米品质、产量及土壤微生物数量和酶活性的影响

To increase our understanding of the advantages of intercropping gramineae crops with legume crops,we conducted a field trial comparing a maize monoculture system,a maize-peanut intercropping system,and a maize-soybean intercropping system with or without application of fertilizer.For each system,we determined maize grain quality(starch,protein,oil,and lysine content),economic and biological yields per plant,crop yield per km2,abundance of microorganisms(bacteria,fungi,actinomycetes,and nitrogen-fixing bacteria) and activities of various enzymes(invertase,dehydrogenase,urease,and phosphatase) in soils(pH=6.2).The field experiment was carried out on upland red soil at the Experimental Station of Jiangxi Agricultural University(latitude 28° 46′N,longitude 115° 36′E,altitude 22.1 m above sea level) from 9 April 2011 to 25 July 2011.The experimental plan comprised six treatments(i.e.,3 × 2) and each treatment was replicated three times.Each plot area was 33 m2(6 m × 5.5 m) and the field experiment had a total of 18 plots.Crop management was the same as that used for local agricultural production.The results showed that maize intercropping significantly increased protein,oil,and lysine content of maize grains when no fertilizer was applied.However,there was no significant effect on starch content of maize grains.When fertilizer was applied,maize intercropping significantly increased starch and lysine content of maize grains,but did not significantly affect oil and protein content.The effect of intercropping on increasing the contents of starch,protein,and lysine in maize grains was not greater than that of nitrogen fertilizer applied at a rate of 50 kg/km2.Intercropping also increased the maize yield(square kilometers) and the biological and economic yield per plant.Compared to the yield from the maize monoculture,that from the maize-peanut and maize-soybean mixed cropping systems was increased by 3.7% and 9.7%,respectively,under unfertilized conditions and by 19.0% and 18.6%,respectively,under fertilized conditions.However,the effect of intercropping on increasing the yield of maize was not greater than that of nitrogen fertilization.Intercropping significantly increased the quantities of soil bacteria,fungi,actinomycetes,and nitrogen-fixing bacteria under different fertilization conditions.Soil enzyme activities were also significantly affected by intercropping.The activity of soil invertase differed significantly between the maize intercropping and monoculture systems in unfertilized conditions,and the activities of soil invertase and phosphatase significantly differed between maize intercropping and monoculture systems under fertilized conditions.A correlation analysis showed that the abundance of the four kinds of microorganisms and the activities of four soil enzymes were significantly(P 0.05) or highly significantly(P 0.01) positively correlated with each other.The maize grain quality,yield,and biological yield per plant were significantly or highly significantly positively correlated with the abundance of microorganisms in soils and with enzyme activities,except for invertase and phosphatase activities.

Dry Matter Production and Yield of Maize-Soybean Intercropping Systems

Dry Matter Production and Yield of Maize-Soybean Intercropping Systems