• Authors:
    • Haeger, A.
  • Source: Agroforestry Systems
  • Volume: 86
  • Issue: 2
  • Year: 2012
  • Summary: Agroforestry systems can mitigate greenhouse gas (GHG) emissions, conserve biodiversity and generate income. Whereas the provision of ecosystem services by agroforestry is well documented, the functional relationships between species composition, diversity and carbon (C)-storage remain uncertain. This study aimed to analyze the effects of management (conventional vs. organic), woody plant diversity and plant composition on aboveground and belowground C-storage in coffee agroforestry systems. It was expected that organic farms would store more C, and that an increase in plant diversity would enhance C-storage due to complementarity effects. Additionally, it was expected that steep slopes decrease C-storage as a result of topsoil erosion. Woody plants were identified on 1 ha plots within 14 coffee farms (7 conventional and 7 organic). C-stocks in trees, coffee plants and roots were estimated from allometric equations. C-stocks in litter and topsoil (0-25 cm) were estimated by sampling. On average, farms stored 93 +/- A 29 Mg C ha(-1). Soil organic carbon accounted for 69 % of total C. Total C-stocks were 43 % higher on organic farms than on conventional farms (P < 0.05). Conventional and organic farms differed in vegetation structure, but not in species diversity. It was found that the combined effect of farm type, species richness, species composition and slope explained 83 % of the variation in total C-storage across all farms (P < 0.001). Coffee agroforestry in general and organic farms in particular may contribute to GHG mitigation and biodiversity conservation in a synergistic manner which has implications for the effective allocation of resources for conservation and climate change mitigation strategies in the agricultural sector.
  • Authors:
    • Kim, D.
  • Source: Agroforestry Systems
  • Volume: 86
  • Issue: 2
  • Year: 2012
  • Summary: Nitrogen (N)-fixing tree and crop intercropping systems can be a sustainable agricultural practice in sub-Saharan Africa and can also contribute to resolving climate change through enhancing soil carbon (C) sequestration. A study conducted by Makumba et al. (Agric Ecosyst Environ 118:237-243, 2007) on the N-fixing tree gliricidia and maize intercropping system in southern Malawi provides a rare dataset of both sequestered soil C and C loss as soil carbon dioxide (CO2) emissions. However, no soil C gain and loss estimates were made so the study failed to show the net gain of soil C. Also absent from this study was potential benefit or negative impact related to the other greenhouse gas, nitrous oxide (N2O) and methane (CH4) emissions from the intercropping system. Using the data provided in Makumba et al. (Agric Ecosyst Environ 118:237-243, 2007) a C loss as soil CO2 emissions (51.2 +/- A 0.4 Mg C ha(-1)) was estimated, amounting to 67.4% of the sequestered soil C (76 +/- A 8.6 Mg C ha(-1) in 0-2 m soil depth) for the first 7 years in the intercropping system. An annual net gain of soil C of 3.5 Mg C ha(-1) year(-1) was estimated from soil C sequestered and lost. Inclusion of the potential for N2O mitigation [0.12-1.97 kg N2O-N ha(-1) year(-1), 0.036-0.59 Mg CO2 equivalents (eq.) ha(-1) year(-1)] within this intercropping system mitigation as CO2 eq. basis was estimated to be 3.5-4.1 Mg CO2 eq. ha(-1) year(-1). These results suggest that reducing N2O emission can significantly increase the overall mitigation benefit from the intercropping system. However, significant uncertainties are associated with estimating the effect of intercropping on soil N2O and CH4 emissions. These results stress the importance of including consideration of quantifying soil CO2, N2O and CH4 emissions when quantifying the C sequestration potential in intercropping system.
  • Authors:
    • Kadyampakeni, D.
    • Fandika, I. R.
    • Zingore, S.
  • Source: Irrigation Science
  • Volume: 30
  • Issue: 1
  • Year: 2012
  • Summary: The performance of a bucket drip irrigation system (BDI) powered by treadle pump was evaluated on tomato and intercropped maize/bean crops, between 2005 and 2007 in Malawi. It was a split plot experiment with three replicates. The BDI system consisted of a 1,300-l tank mounted 1.5 m above ground and connected with a 32-mm mainline and 15-mm lateral lines spaced at 1 m by 0.6 m. A treadle pump was used to uplift water to the tank. Tomato and intercropped maize/bean were irrigated every 4 days. The system reduced labour and water by >25% and it showed high uniform application depth and wetted diameter. Yields were significantly different between tomato varieties ( P
  • Authors:
    • Bakshawain, A. A.
    • Abusuwar, A. O.
  • Source: African Journal of Microbiology Research
  • Volume: 6
  • Issue: 14
  • Year: 2012
  • Summary: A field experiment was carried out during 2009/2010 and 2010/2011 seasons at Hada Al-Sham experimental Farm of King A/Aziz University in Jeddah, Saudi Arabia. The objective was to evaluate the effect of some chemical fertilizers on productivity and nutritive value of Sorghum Sudanense Var. Panar intercropped with Cowpea ( Vigna unguiculata L. Walp) in an adverse condition of soil and irrigation water. The chemical fertilizers applied were 50 kg/ha of urea (46%N), 50 kg/ha of triple superphosphate (46% P), 50 kg/ha of KNO 3, 50 kg/ha of NPK (20:20:40) and a control for check. Sudan grass and Cowpea were sown as sole crops and as a mixture. Treatments were laid out in a split plot design with the fertilizer treatments in the main plots and the intercropping treatments in the subplots. Parameters measured were plant height and nutritive value for the Sudan grass, fresh and dry yields and the land equivalent ratio (LER). The chemical fertilizers had no significant (P≤0.05) effect on productivity but significantly improved forage quality. Intercropping of Sudan grass and Cowpea significantly (P≤0.05) increased forage productivity and improved forage quality and land equivalent ratio (LER). Cowpea was not a good competitor as it disappeared following the first cut in the first season.
  • Authors:
    • Kussman, R. D.
    • Kremer, R. J.
  • Source: Agroforestry Systems
  • Volume: 83
  • Issue: 2
  • Year: 2011
  • Summary: Intercropping alleys in agroforestry provides an income source until the tree crop produces harvestable yields. However, cultivation of annual crops decreases soil organic matter and increases soil erosion potential, especially on sloping landscapes. Perennial crops maintain a continuous soil cover, increase water infiltration, reduce soil erosion, and improve overall soil quality. The objective of this on-farm study was to assess the effects of a perennial legume, kura clover ( Trifolium ambiguum M. Bieb.), on soil quality in a recently established pecan ( Carya illinoinensis Wangenh. C. Koch) orchard. The pecan-kura clover agroforestry practice was established on deep loess soils of the Missouri River hills landscape. These silt loams are on 2-20% slopes and can be highly erosive. Kura clover, introduced as the alley crop 5 years after pecan planting, was selected based on its perennial growth habit, nitrogen-fixing ability, winter hardiness, high forage quality, and soil conservation properties. Kura clover was seeded in 2001 and harvested for hay annually beginning 2003. Soil quality indicators of total organic C, total N, water-stable aggregates, and selected soil enzymes were determined on surface soil samples collected annually after kura clover establishment. Soil organic C and activities of soil enzymes increased compared with cultivated and grass pasture control soils by the eighth year of establishment. Water-stable aggregation improved by 50% and surface soil shear strength improved significantly ( P<0.05) in alleys compared with control sites. Results illustrate that kura clover as the alley-cropped component improved soil fertility and biological activity through increased organic matter and improved soil structure, and yielded high quality forage valuable for the cattle-feeding operation. Kura clover maintained or improved soil quality, reduced soil erosion potential, and benefited pecan growth by providing a source of soil nitrogen and improving soil structure for adequate water infiltration and aeration.
  • Authors:
    • Buzetti, S.
    • Bergamaschine, A. F.
    • Ulian, N. de A.
    • Pariz, C. M.
    • Furlan, L. C.
    • Andreotti, M.
    • Meirelles, P. R. de L.
    • Cavasano, F. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: The greatest limitation to the sustainability of no-till systems in Cerrado environments is the low quantity and rapid decomposition of straw left on the soil surface between fall and spring, due to water deficit and high temperatures. In the 2008/2009 growing season, in an area under center pivot irrigation in Selviria, State of Mato Grosso do Sul, Brazil, this study evaluated the lignin/total N ratio of grass dry matter, and N, P and K deposition on the soil surface and decomposition of straw of Panicum maximum cv. Tanzania, P. maximum cv. Mombaca, Brachiaria brizantha cv. Marandu and B. ruziziensis, and the influence of N fertilization in winter/spring grown intercropped with maize, on a dystroferric Red Latosol (Oxisol). The experiment was arranged in a randomized block design in split-plots; the plots were represented by eight maize intercropping systems with grasses (sown together with maize or at the time of N side dressing). Subplots consisted of N rates (0, 200, 400 and 800 kg ha -1 year -1) sidedressed as urea (rates split in four applications at harvests in winter/spring), as well as evaluation of the straw decomposition time by the litter bag method (15, 30, 60, 90, 120, and 180 days after straw chopping). Nitrogen fertilization in winter/spring of P. maximum cv. Tanzania, P. maximum cv. Mombaca, B. brizantha cv. Marandu and B. ruziziensis after intercropping with irrigated maize in an integrated crop-livestock system under no-tillage proved to be a technically feasible alternative to increase the input of straw and N, P and K left on the soil surface, required for the sustainability of the system, since the low lignin/N ratio of straw combined with high temperatures accelerated straw decomposition, reaching approximately 30% of the initial amount, 90 days after straw chopping.
  • Authors:
    • Pinto, C.
    • Sizenando Filho, F.
    • Cysne, J.
    • Pitombeira, J.
  • Source: Revista Verde de Agroecologia e Desenvolvimento Sustentavel
  • Volume: 6
  • Issue: 2
  • Year: 2011
  • Summary: Field experiments were conducted in Ceara, Brazil, to study the response of castor bean intercropping with sesame, cotton, maize and cowpea under dryland conditions. The intercropping indices evaluated were LER, LEC, ATER, mean of LER and ATER, SPI, CoR, RCC, CR, A and ALY. Castor beans and intercrops had reductions in yield. Based on the LER, LEC, CRA, AYL and CoR in the intercropping systems, the castor bean + maize treatment was the most advantageous under dryland farming. Based on the A and ALY indices, castor bean was dominated by sesame, cotton, maize and cowpea. The castor bean, cotton, sesame and castor bean, castor bean, maize treatments showed yield stability, which was characterized by the productivity index of the system (SPI).
  • Authors:
    • Pauletti, V.
    • Piva, J.
    • Santos, N.
    • Dieckow, J.
    • Bayer, C.
    • Molin, R.
    • Favaretto, N.
  • Source: Soil & Tillage Research
  • Volume: 111
  • Issue: 2
  • Year: 2011
  • Summary: To improve C sequestration in no-till soils requires further development of crop rotations with high phytomass-C additions. The objectives of this study were (i) to assess long-term (17 years) contributions of cover crop- or forage-based no-till rotations and their related shoot and root additions to the accumulation of C in bulk and in physical fractions of a subtropical Ferralsol (20-cm depth); and (ii) infer if these rotations promote C sequestration and reach an eventual C saturation level in the soil. A wheat ( Triticum aestivum L., winter crop)-soybean ( Glycine max (L.) Merr, summer crop) succession was the baseline system. The soil under alfalfa ( Medicago sativa L., hay forage) intercropped every three years with maize ( Zea mays L., summer crop) had the highest C accumulation (0.44 Mg C ha -1 year -1). The bi-annual rotation of ryegrass ( Lolium multiflorum Lam., hay winter forage)-maize-ryegrass-soybean had a soil C sequestration of 0.32 Mg C ha -1 year -1. Among the two bi-annual cover crop-based rotations, the vetch ( Vicia villosa Roth, winter cover crop)-maize-wheat-soybean rotation added 7.58 Mg C ha -1 year -1 as shoot plus root and sequestered 0.28 Mg C ha -1 year -1. The counterpart grass-based rotation of oat ( Avena strigosa Schreb., winter cover crop)-maize-wheat-soybean sequestered only 0.16 Mg C ha -1 year -1, although adding 13% more C (8.56 Mg ha -1 year -1). The vetch legume-based rotation, with a relative conversion factor (RCF) of 0.147, was more efficient in converting biomass C into sequestered soil C than oat grass-based rotation (RCF=0.057). Soil C stocks showed a close relationship ( R2=0.72-0.98, P<0.10) with root C addition, a poor relationship with total C addition and no relationship with shoot C addition. This suggests a more effective role of root than shoot additions in C accumulation in this no-till soil. Most of the C accumulation took place in the mineral-associated organic matter (71-95%, in the 0-5 cm layer) compared to the particulate organic matter. The asymptotic relationship between root C addition and C stocks in bulk soil and in mineral-associated fraction supports the idea of C saturation. In conclusion, forages or legume cover crops contribute to C sequestration in no-till tropical Ferrasols, and most of this contribution is from roots and stored in the mineral-associated fraction. This combination of soil and rotations can reach an eventual soil C saturation.
  • Authors:
    • Li, H.
    • Cheng, J.
    • Zhang, J.
    • Yue, T.
    • Xi, Z.
  • Source: Scientia Agricultura Sinica
  • Volume: 44
  • Issue: 11
  • Year: 2011
  • Summary: Objective: In this paper, the relationship between soil quality and soil biological characteristics such as soil microorganism quantity and soil enzymatic activity was studied in the intercropping system of vineyard, in order to illustrate the function of soil biological characteristics as bio-indicators of soil fertility. Method: Three such cover crops, two perennial legumes (white clover and alfalfa) and a perennial gramineous grass (tall fescue) were sown in vineyard. Soil microorganism quantity, soil enzymatic activities and soil nutrient content were analyzed and compared with that in soil cultivation. [Result] Most detected soil microorganism quantity and soil enzymatic activity, soil organic matter were increased under cover crop treatments, compared to clean tillage, tall fescue treatment decreased urease and sucrase activity. White clover and alfalfa treatments significantly increased the contents of hydrolyzable N, total N and available K, and tall fescue decreased them, while the activated organic P in tall fescue treatment was more effectively than that in white clover and alfalfa treatments. Correlation analysis indicated that soil organic matter, total N, hydrolyzable N, total P, available K showed significant or very significant positive correlation with 10 soil biological characteristic factors such as bacteria, fungi, actinomyces, azotobacter, cellulose-decomposing bacteria, urease, phosphatase, amylase, sucrase, and cellulose. The catalase activity was no significant correlation with all the soil nutrient contents, and the total K content was no significant correlations with all the soil biological characteristic factors. The soil pH in this experiment was negatively correlated with soil biological properties. Conclusion: Cover crops in the inter-rows of vineyard increased soil microorganism quantity, soil enzymatic activity and soil nutrient content, white clover and alfalfa treatments were better than tall fescue. There are significant correlations between soil biological characteristics and nutrients, and soil biological indexes could reflect the changes of soil quality.
  • Authors:
    • Sharawy, W.
    • Abdel-Hafeez, A.
    • Abdel-Gawad, K.
    • El-Nabawy, W.
  • Source: Bulletin of Faculty of Agriculture, Cairo University
  • Volume: 62
  • Issue: 4
  • Year: 2011
  • Summary: Two field experiments were conducted at the Agricultural Experiments and Research Station, Faculty of Agriculture, Cairo University, Giza, Egypt, during 2008 and 2009 summer seasons, to study the intercropping of forage cowpea ( Vigna unguiculata L., var. Buff) with maize ( Zea mays L), stay green and single cross hybrid 122. The experiment was planted at the 1st of July after wheat in both seasons. The experimental design was a split-split plot design arranged in randomized complete blocks with three replicates. The main plots were devoted to three intercropping patterns: (1) Maize on one side of the ridge and forage cowpea on the other side, (2) Solid maize, (3) Solid forage cowpea. Subplots were arranged with plant density of forage cowpea, one and two plants hill -1 at 20 cm between hills. Sub-sub plots were four nitrogen levels viz., zero, 60, 90 and 120 kg N fed. -1 N was added in two equal doses after 21 and 60 days from planting (after the 1st cut of forage cowpea). The results indicated significant differences between intercropping patterns, plant density and nitrogen levels for dry yield. Light intensity at top, middle and bottom of cowpea and maize were obtained at each cut in both seasons. light intensity under solid cowpea was greater for the three levels of light intensity reading than intercropped cowpea plants. At the top of intercropped cowpea plants, light intensity was greater as compared with readings at the middle and bottom of plants. At the middle, light intensity was greater for solid cowpea compared to intercropped cowpea. One plant hill -1 was superior to two plants hill -1 in light intensity at top, middle and bottom of cowpea plants intercropped with maize at each cut in both seasons. The percentage of increases in light intensity gave lower values between the two plant intensities, it could be recommended with planting two plants hill -1 when intercropped cowpea with maize for obtaining high dry forage yield of cowpea. Nitrogen application was significantly decreased light intensity at top, middle and bottom plant of forage cowpea at each cut in both seasons. Nitrogen from zero to 120 kg N fed -1 caused reduction in light intensity, While total dry forage yield of cowpea was increased. The highest value of light intensity was obtained by solid cowpea, one plant hill -1 and zero nitrogen fed -1, while the lowest value of light intensity was at intercropped cowpea with maize, two plants hill -1 and 120 kg N fed. -1 For maize plants there were significant differences in light intensity as affected by intercropping patterns at top, middle bottom of maize plants in both seasons except between intercropping two plants hill -1 of cowpea with maize and solid maize at top plant before the 1st cut of cowpea in the first season. Nitrogen levels was significantly decreased light intensity at top, middle and bottom plant of maize, with not significant differences between 90 and 120 kg N fed. -1 While, grain yield and dry stover yield were increased. Zero N level had the highest value of light intensity at top, middle and bottom of maize plants compared with the other N levels. The highest value was obtained by solid maize and zero nitrogen fed, -1 while the lowest value was at intercropping two plants hill -1 of cowpea with maize and 120 kg N fed -1.