• Authors:
    • Quideau, S.
    • Pswarayi, A.
    • Nelson, A. G.
    • Frick, B.
    • Spaner, D.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 3
  • Year: 2012
  • Summary: To investigate intercropping as a management strategy to increase crop productivity and weed suppression in organic systems, spring wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), canola ( Brassica napus L.) and field pea ( Pisum sativum L.) monocultures were compared with two-, three-, and four-crop intercrops containing wheat at two organic and one conventional site in 2006 and 2007, central Alberta, Canada. We measured crop and weed biomass, grain yield, and crop competitiveness against weeds from a replacement design in a completely randomized block experiment. Pea and canola monocrops on organic sites yielded the least of all crop treatments. Conventional crop treatments generally yielded higher than organic treatments. Few land equivalent ratios (LERs) on organic sites were significantly >1.0. Some wheat intercrops without barley showed overyielding (LER >1.0) potential. Most of the significant LERs were from three- and four-crop intercrops. More than 50% of the intercrops on organic sites significantly suppressed weeds (based on relative weed biomass) and most of these intercrops had barley in the mixture. Barley as a sole crop and in intercrops suppressed weeds better than all other intercrops and sole crops. The wheat-canola intercrop exhibited the best weed suppression of the two-crop intercrops on organic and conventional sites. The crop densities used in this study may have contributed to the extremely low pea and canola monocrop yields as well as low LERs. Due to this, our findings should be regarded as showing trends and potential from intercrops only. We therefore recommend further studies to establish ideal densities for the intercrops used.
  • Authors:
    • Gaillard, B.
    • Foissy, D.
    • Dorvillez, D.
    • Carrouee, B.
    • Boucheny, P.
    • Biarnes, V.
    • Bedoussac, L.
    • Baranger, E.
    • Al-Rifai, M.
    • Naudin, C.
    • Corre-Hellou, G.
    • Makowski, D.
    • Bazot, M.
    • Pelzer, E.
    • Guichard, L.
    • Mansard, M.
    • Omon, B.
    • Prieur, L.
    • Yvergniaux, M.
    • Justes, E.
    • Jeuffroy, M.
  • Source: European Journal of Agronomy
  • Volume: 40
  • Year: 2012
  • Summary: Intensive agriculture ensures high yields but can cause serious environmental damages. The optimal use of soil and atmospheric sources of nitrogen in cereal-legume mixtures may allow farmers to maintain high production levels and good quality with low external N inputs, and could potentially decrease environmental impacts, particularly through a more efficient energy use. These potential advantages are presented in an overall assessment of cereal-legume systems, accounting for the agronomic, environmental, energetic, and economic performances. Based on a low-input experimental field network including 16 site-years, we found that yields of pea-wheat intercrops (about 4.5 Mg ha -1 whatever the amount of applied fertiliser) were higher than sole pea and close to conventionally managed wheat yields (5.4 Mg ha -1 on average), the intercrop requiring less than half of the nitrogen fertiliser per ton of grain compared to the sole wheat. The land equivalent ratio and a statistical analysis based on the Price's equation showed that the crop mixture was more efficient than sole crops particularly under unfertilised situations. The estimated amount of energy consumed per ton of harvested grains was two to three times higher with conventionally managed wheat than with pea-wheat mixtures (fertilised or not). The intercrops allowed (i) maintaining wheat grain protein concentration and gross margin compared to wheat sole crop and (ii) increased the contribution of N 2 fixation to total N accumulation of pea crop in the mixture compared to pea sole crop. They also led to a reduction of (i) pesticide use compared to sole crops and (ii) soil mineral nitrogen after harvest compared to pea sole crop. Our results demonstrate that pea-wheat intercropping is a promising way to produce cereal grains in an efficient, economically sustainable and environmentally friendly way.
  • Authors:
    • Wu, L.
    • Li, F.
    • Zhu, O.
    • Sun, Z.
  • Source: Journal of Resources and Ecology
  • Volume: 3
  • Issue: 1
  • Year: 2012
  • Summary: The major function of clover in a winter wheat-white clover intercropping system is to supply nitrogen (N) for the wheat. A field experiment was conducted at Yucheng Comprehensive Station of the Chinese Academy of Sciences, to evaluate the effect of cutting white clover on N fixation and the transfer of fixed N to the associated winter wheat. A method of 15N natural abundance was used to determine the nitrogen dynamics in the intercropping system. The results showed that the amount of N transferred from the clover to the wheat, throughout the growing season, varied between 34.4 and 57.5 kg ha -1. Compared to leaving the clover standing, cutting the clover increased the amount of N that accumulated in the soil and also resulted in reduced N concentrations in the leaves and stems of the wheat. Using the cut clover as mulch between wheat rows led to decreased N concentrations in the wheat plants' leaves and stems. The present study provides preliminary information on the amount of N transferred from clover to wheat in an intercropping system.
  • Authors:
    • Wan, Y.
    • Chen, X.
    • Xiang, D.
    • Yang, W.
    • Yong, T.
  • Source: Acta Prataculturae Sinica
  • Volume: 21
  • Issue: 1
  • Year: 2012
  • Summary: The aim of this paper was to study the variation of interspecies competitiveness in two relay strip intercropping system; wheat-maize-soybean and wheat-maize-sweet potato. The character of biomass accumulation and nitrogen uptake were examined for five cropping systems using years of field experiment. The cropping systems included three sole cropping systems (wheat-soybean, wheat-sweet potato and maize) and two relay strip intercropping systems (wheat/maize/soybean and wheat/maize/sweet potato). Land equivalent ratio (LER), aggressiveness (A), and nutrition competition ratio (NCR) were introduced as indexes to evaluate the interspecies competitiveness in each treatment. The results showed that there was obvious relay strip intercropping advantage ( LER >1, Awc 1) in the wheat-maize-soybean relay strip intercropping system, maize occupied the dominant niche for the whole growing stage in the relay strip intercropping systems, and the interspecies competitiveness of wheat and soybean were lower than that of the maize. Comparing with the sole cropping systems and wheat-maize-sweet potato relay strip intercropping system, the grain yield and nitrogen uptake, total biomass and total nitrogen uptake above ground of crops were increased significantly at both flowering (or spinning) and maturity stages in the wheat-maize-soybean relay strip intercropping system. The values of biomass and nitrogen uptake for the relay strip intercropping system were greater than the sole cropping systems, and that of soybean stubble were greater than sweet potato stubble. The total economic returns of crops in the wheat/maize/soybean relay strip intercropping system was higher 28.02% than those of crops in the wheat/maize/sweet potato relay strip intercropping system.
  • Authors:
    • Zhu, Z.
    • Xiang, D.
    • Yang, W.
    • Yong, T.
  • Source: Acta Agronomica Sinica
  • Volume: 38
  • Issue: 2
  • Year: 2012
  • Summary: The aim of this study was to understand the relationship between diversity of rhizosphere bacterial community and nitrogen uptake of crops in two relay strip intercropping systems: wheat/maize/soybean and wheat/maize/sweet potato. We analyzed the diversities of rhizosphere bacterial community in five cropping systems using denaturing gradient gel electrophoresis (DGGE) based on 16S rDNA. The cropping systems included wheat-soybean (A1), wheat-sweet potato (A2), maize single cropping (A3), wheat/maize/soybean (A4), and wheat/maize/sweet potato (A5). Compared to the sole cropping systems (A1, A2, and A3 treatments), the A4 treatment showed increases in grain nitrogen uptake and total nitrogen uptake amounts of aboveground of crops at both flowering (or silking) and maturity stages, and the Shannon-Weiner indices for rhizosphere bacterial community diversity was also increased significantly. The values of nitrogen uptake and the Shannon-Weiner index in the relay strip intercropping systems were greater than those in sole cropping systems, and the values in the treatment with soybean stubble were greater than those in the treatment with sweet potato stubble. The number and strength of the DNA bands from DGGE profiles varied with the cropping systems, especially for the distinguished bands. The comparability of rhizosphere bacterial community composition was low among different cropping systems. The similarity coefficient ( Cs) was higher between two relay strip intercropping systems than between relay strip intercropping system and sole cropping system, but the Cs value was low between A4 and A5 treatments. However, there was obvious difference of rhizosphere bacterial community composition between A4 and A5 treatments, and the A4 treatment was propitious to enhancing rhizosphere bacterial community diversity and increasing nitrogen uptakes of crops.
  • Authors:
    • Shi, H.
    • Luo, Y.
    • Xue, J.
    • Wu, D.
  • Source: Journal of Nanjing Forestry University (Natural Sciences Edition)
  • Volume: 36
  • Issue: 2
  • Year: 2012
  • Summary: By using in situ leaching device, a field experiment was conducted to study the nitrate leaching amount and density at 60 cm soil depth, nitrate accumulation in soil profile (0-80 cm) of poplar-wheat intercropping ecosystem. Four treatments were installed, no fertilization (N 0, 0 kg/hm 2) conventional fertilization (N 140, 140 kg/hm 2), reduced N application (N 70, 70 kg/hm 2), increased N application (N 210, 210 kg/hm 2). The results indicated a positive correlation between quantity of leachate water and precipitation, the poplar-wheat intercropping ecosystem can reduce the quantity of eluviate solution. The nitrate leaching loss increased according to the increasing N fertilization rate. In treatment spot N 210, the nitrate nitrogen loss from N fertilization at 60 cm soil depth was the greatest (13.89 kg/hm 2), it declined by 60.27% and 50.11% in poplar-wheat intercropping ecosystem away from the poplar row 0.5 m and 1.5 m, respectively. The nitrogen leaching and accumulation were significantly lower in poplar-wheat intercropping ecosystem, and variances of the distribution for soil nitrate nitrogen were significant.
  • Authors:
    • Li, Y.
    • Liu, G.
    • Yang, L.
    • Ma, L.
    • Xia, L.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 28
  • Issue: 14
  • Year: 2012
  • Summary: Protective management of arable slope land plays an important role in protection of land resource and aquatic environment in Three Gorges region, China. Base on the regional natural conditions and the utilization of the arable slope land, four tillage modes with H1 (rotation of wheat and maize, wheat intercropped with horse bean, less tillage and ridge cultivation), H2 (rotation of wheat and maize, with Vetiveria ziz anioides contour hedges intercropped at slop length interval of 5 m), H3 (rotation of wheat and maize, with alfalfa contour hedges intercropped at slop length interval of 5 m), H4 (rotation of wheat and maize, conventional management) were conducted from Oct. 2009 to Oct. 2011. The differences of apparent recovery efficiency and Agronomic efficiency of applied nitrogen and phosphorus between treatments were discussed, as well as nitrogen and phosphorus losses through slope land surface runoff were analyzed. The results showed that compared with H4, H1 increased phosphorus use efficiency by 0.06 kg/kg. No significant difference of biological and economic production, apparent recovery efficiency and agronomic efficiency of applied nitrogen and phosphorus was observed among H2, H3 and H4, which showed intercropping with Vetiveria ziz anioides or alfalfa contour hedges wouldn't lead to the reduction of production. Furthermore significant effects on reducing soil erosion and sediment phosphorus loss were observed for H1, H2 and H3. Compared with H4, and sediment losses for H1, H2 and H3 decreased by 48.46%, 52.26% and 58.59% respectively, and sediment phosphorus losses decreased by 30.58%, 47.70% and 44.58% respectively.
  • Authors:
    • Francis, F.
    • Liu, Y.
    • Sun, J.
    • Zhou, H.
    • Cheng, D.
    • Chen, J.
    • Xie, H.
  • Source: Journal of Economic Entomology
  • Volume: 105
  • Issue: 3
  • Year: 2012
  • Summary: The effects of intercropping wheat, Triticum aestivum L., with mung bean, Vigna radiate L., on the populations of English grain aphid, Sitobion avenae (F.) (Hemiptera: Aphididae), and its natural enemies were evaluated by field and laboratory experiments. The population densities of aphids and their natural enemies were evaluated in the intercropped field against different row ratio combinations of wheat-mung bean. Results showed that wheat-mung bean intercropping caused a drop in aphid densities, and the ratio 12 wheat:4 mung bean brought about the largest drop (>18%). In addition, the population densities of coccinellids (ladybirds) and parasitoids and the species diversity of all the natural enemies of aphid were higher in the intercropped field than in the field planted only with wheat. However, intercropping did not influence the community indices (evenness and index of dominance concentration) of the natural enemies. Y-tube olfactometer bioassays were carried out in the laboratory to test whether odor blends of host and nonhost plants affect the host selection of S. avenae. Bioassays indicated that both apterous and alate aphids significantly preferred host plant odor over odor blends of host and intercropped species. Hence, the olfactory-based host location of aphids in the field might be affected by intercropping. The intercropping experiment clearly showed that increased crop species diversity suppresses aphid population growth and preserves the population of natural enemies of aphids. Our results also provide support for the "resource concentration hypothesis" and the "enemies hypothesis".
  • Authors:
    • Yahuza, I.
  • Source: International Journal of Biosciences (IJB)
  • Volume: 2
  • Issue: 6
  • Year: 2012
  • Summary: Five experiments agronomically managed differently investigated yield-density relationships in wheat/faba bean (bean) intercropping system. For the wheat sole crop, seed yield (SY) ranged from 102 g/m 2 to 734 g/m 2. Intercropping reduced wheat SY but this did not always depend on wheat seed rate (wsr). Standard intra-specific and/or inter-specific yield-density equations derived from the literature and others modified here were used to quantify the SYs (as was applicable). For the majority of the experiments wheat SYs, whether sole cropped or intercropped responded asymptotically as wsr increased. The maximum bean sole crop SY was 392 g/m 2: bean SY declined as wsr increased. The total intercrop (wheat+bean) SY response to wsr was asymptotic in at least two of the experiments, following similar pattern as the wheat. Although, for the mean effects of intercropping the total intercrop SYs was substantial in three experiments; the total intercrop did not produce significantly greater SY than the wheat sole crop as wsr increased. Moreover, maximum wheat sole crop and wheat intercrop SYs were significantly greater under the organically-managed experiment than the conventional-managed one, even though they were both established in the same cropping year. Similarly, as regards wheat SYs, comparisons of spring-sown with the winter-sown crops established in the same cropping year indicate that the former performed better than the latter. Nevertheless, for most of the experiments investigated here, this research indicates that 100-wheat seeds/m 2 or lower may be appropriate to intercrop with bean at 30 to 40-bean seeds/m 2 to reduce competition and improve productivity.
  • Authors:
    • Zhang, P.
    • Lu, C.
    • Xie, H.
    • Gong, P.
    • Yang, L.
    • Yang, B.
    • Xu, Y.
    • Zhang, W.
  • Source: Xinjiang Agricultural Sciences
  • Volume: 49
  • Issue: 3
  • Year: 2012
  • Summary: Objective: The purpose of this project was to provide theoretical basis for the selection of suitable almond shape in almond-wheat intercropping systems through the research of four different almond tree cultivation shapes' canopy, photosynthetic rate and micro environment indicators, and the effect on lighting distribution and growth behaviors of intercropping wheat. Method: Ten years-old Wanfeng-almond trees were used as testing materials, and four structure treatments such as trunk-delaminating shape, open-center shape, spindle shape and high-stem round capitiform were set to study the difference among those four tree shapes and survey lighting distribution and wheat growth condition. Result: The load of per spindle shape tree was 1,184 per plants, which was lower than trunk-delaminating treatment. Due to small canopy volume of spindle shape, the load of unite projection plane was the highest, reaching 94.8 per m 2, and it was 2.06 times of trunk-delaminating treatment. The spindle shape tree's inner crown lighting distribution condition was better than other three treatments, reaching 31% of nature condition. Effect of spindle shape treatment on overshadow of intercropping area was lower, and stained lightly. The light intensity of overall intercropping area and at the both sides of the near crown areas was respectively 40.89% and 34.57% of nature condition. Conclusion: The preliminarily research showed that the spindle tree had high yield and lower influence on intercropping area, and it is suitable for the tridimensional composite planting system.