• Authors:
    • Florio, G.
    • Brigi, A.
    • Sandrini, S.
    • Bona, S.
    • Coletto, L.
    • Sambo, P.
  • Source: Proceedings of the Conference on integrated assessment of agriculture and sustainable development: Setting the Agenda for Science and Policy (AgSAP 2009), Hotel Zuiderduin, Egmond aan Zee, The Netherlands, 10-12 March 2009
  • Year: 2009
  • Authors:
    • Darbyshire, S.
    • Clements, D.
    • DiTommaso, A.
    • Dauer, J.
  • Source: Canadian Journal of Plant Science
  • Volume: 89
  • Issue: 5
  • Year: 2009
  • Summary: Hemp dogbane, Apocynum cannabinum (Apocynaceae), is a perennial herb with white to greenish flowers in terminal clusters that produces pencil-like pods 12-20 cm long. A highly variable plant, A. cannabinum may be distinguished from spreading dogbane ( Apocynum androsaemifolium) by its shorter corolla (2-6 mm compared with 5-10 mm), erect greenish-white petals (compared with recurved or spreading pinkish petals), seeds more than 3 mm long (compared with seeds less than 3 mm), and more erect leaves (compared with spreading or drooping leaves), although frequent hybridization between the two species obscures the identity of some individuals. Hemp dogbane is native to the United States and southern Canada, but most abundant in the upper Mississippi River Valley and east to the Atlantic coast. It has been increasing in other areas, and becoming more of a problem where conservation tillage is adopted. It infests crops such as corn ( Zea mays), soybeans ( Glycine max), wheat ( Triticum aestivum), sorghum ( Sorghum bicolor) and forages, and may cause livestock poisoning due to cardiac glycosides within its milky sap (but livestock generally avoid it). Potential medicinal uses of these compounds have been investigated, and the roots are a source of fibre. Control of A. cannabinum with various herbicides is difficult due to a thick cuticle, and one solution may be to target susceptible stages, such as seedlings or early spring growth. Cultivation may also control A. cannabinum, but care must be taken not to promote the proliferation of the plant through regrowth from fragmented roots and rhizomes. Rotation with alfalfa also reduces populations of A. cannabinum.
  • Authors:
    • Gentry, T.
    • Aitkenhead-Peterson, J.
    • Gonzalez-Chavez, M.
    • Zuberer, D.
    • Hons, F.
    • Loeppert, R.
  • Source: Soil & Tillage Research
  • Volume: 106
  • Issue: 2
  • Year: 2009
  • Summary: Tillage and crop rotation/intensity can influence soil biological properties and relevant soil processes including C sequestration. This study determined the effects of long-term (25 years) no till (NT) and conventional tillage (CT) management and cropping sequence [continuous wheat (CW; Triticum aestivum L.) and a rotation of sorghum ( Sorghum bicolor L. Moench), wheat and soybean (RW; Glycine max L. Merr)] on soil microbial community structure and labile and recalcitrant microbial bio-products in central Texas. Fatty acid methyl ester (FAME) profiles, microbial biomass (MB-C, -N and -P), hot water extractable soil carbohydrates (HWE-SC) and easily extracted- (EE-) and total-glomalin-related soil proteins (T-GRSP) were analyzed. Principal component analysis of the FAME data indicated that crop management modified and selected microbial populations. In general, NT-RW resulted in the greatest richness and biodiversity of the total microbial community, soil organic C, MB-P, HWE-SC, EE- and T-GRSP. No tillage increased labile and more recalcitrant bio-products, soil organic C and total N compared to CT. The soil microbial biomass C:N:P ratio, an indicator of ecosystem nutrient limitation, suggested that the CT-RW treatment may have a soil P limitation, which was not observed in the other treatments. The treatments preferentially selected for different microbial communities, which generated microbial products that significantly influenced soil C and N retention. Our results suggested that NT in conjunction with crop rotation (RW) can be recommended for increased soil C sequestration.
  • Authors:
    • Zorza, E.
    • Perez, L.
    • Perez, M.
    • Rainero, H.
    • Rodriguez, N.
    • Leguizamon, E.
    • Fernandez-Quintanilla, C.
  • Source: Weed Research
  • Volume: 49
  • Issue: 1
  • Year: 2009
  • Summary: Field trials were established in various growing seasons in four experimental sites with soyabeans or maize grown under no tillage systems. Seeds of Digitaria sanguinalis, Eleusine indica, Sorghum halepense, Setaria geniculata, Echinochloa colonum and Urochloa platyphylla were incorporated in surface soil, under the crop residues of the previous season, each autumn. Regular records of seedling emergence during the following spring and summer were used to model the pattern of each species as a function of the thermal time in the 2 cm upper layer of the soil profile. A Weibull function closely described ( r2=0.73-0.93) the relationship between thermal time and seedling emergence for all species in each site and year. The coefficient of determination for the model verification ranged from 0.71 to 0.98. Species may be grouped into three emergence time-span groups. Eleusine indica, U. platyphylla and E. colonum had a long-lasting emergence, requiring 940-1660 ddegreesC (growing day degrees) to complete this process. Digitaria sanguinalis and S. halepense had an intermediate emergence time-span, completing this process in 540-1090 ddegreesC. Setaria geniculata exhibited the shortest emergence time-span (290-660 ddegreesC required for full emergence). Different hypotheses were tested in order to explain species model parameter differences in different sites and to establish the basis for more refined models with improved prediction capabilities.
  • Authors:
    • Garcia, R.
    • Dornelles, M.
    • Lima, A.
    • Coelho, F.
    • Lima, E.
  • Source: Revista Ceres
  • Volume: 56
  • Issue: 6
  • Year: 2009
  • Summary: The objective of this work was to evaluate a number of soybean agronomic characteristics in green manuring succession with two types of residue management. An experiment arranged in a complete randomized block design with four repetitions distributed in a split-plot scheme was carried out in Campos dos Goytacazes-RJ, in the agricultural year 2001/2002. The plots consisted of two managements (with and without clipping) and the subplots consisted of the cover species (black oat, millet, forage sorghum, teosinte, forage radish, dwarf velvet bean, white lupin, pigeonpea, and spontaneous vegetation). In the treatment without clipping, the mean grain yield of soybean in succession with black oat and spontaneous vegetation was 50% higher than the succession with dwarf velvet bean, millet, pigeonpea and forage sorghum. However, in the treatment with clipping, the mean grain yield in succession with millet, teosinte and spontaneous vegetation was 79% higher than the succession with lupin and dwarf velvet bean. The management of millet with mechanical clipping resulted in the increase of 1.154 kg ha -1 of soybean compared wih the treatment without management.
  • Authors:
    • Nakagawa, J.
    • Cavariani, C.
    • Crusciol, C.
    • Lima, E.
  • Source: Revista Brasileira de Sementes
  • Volume: 31
  • Issue: 1
  • Year: 2009
  • Summary: Soybean productivity under the no till system (NTS) can be influenced by the preceding type of plant cover and surface liming. However, the effects of this technique on yield components and the seed physiological quality have been little studied, especially in ("safrinha") off-season soybean under NTS. Therefore, this study aimed to evaluate some agronomic traits, yield components, productivity, and physiological quality of soybean grown during the off-season ("safrinha"), as a function of different cover plants, with or without surface liming, under NTS. The experiment was conducted during the 1999/00 cropping season on the Lageado Experimental Farm, FCA/UNESP/Botucatu-SP, Brazil. The experimental design was organized as randomized blocks in split-plots, with 4 replications. The 6 m * 10 m plots consisted of broomcorn ( Sorghum bicolor), millet ( Pennisetum americanum), fall panicum ( Panicum dichotomiflorum), spontaneous vegetation, and no vegetation. At 53 days after emergence the cover plants were desiccated and lodged, and a surface application of 3.1 t.ha-1 lime was made in half of the plots, in order to increase V% to 70. Soybean (cv. IAC-19) was sown two weeks later, during the off-season ("safrinha"). Determinations were made for the final stand, first pod height, plant height, total number of pods and blank pods per plant, total number of seeds per pod, 100-seed weight and yield. As to seed physiological quality, determinations were made for germination, artificial aging, germination at 18C, plantlet D.M., and electric conductivity. During NTS implementation, plant cover type and surface liming did not affect the agronomic traits studied, yield components, seed productivity, and physiological quality of soybean seeds grown in the off-season ("safrinha") system, except for electric conductivity.
  • Authors:
    • Cargnelutti Filho, A.
    • Assis, R.
    • Procopio, S.
    • Monteiro, F.
    • Pires, F.
    • Pacheco, L.
    • Carmo, M.
    • Petter, F.
  • Source: Planta Daninha
  • Volume: 27
  • Issue: 3
  • Year: 2009
  • Summary: The objective of this experiment was to evaluate the efficiency of soybean oversowing, using cover crops, in reducing weed emergence and its reflections on the productivity of the soybean cultivated in the following season. The experiment was arranged in a randomized block design, in split-plot, with four replications. The soybean was sown four times: (1) 10/27/2005, (2) 11/10/2005, (3) 11/24/2005 and (4) 12/14/2005, under a no-tillage system, corresponding to four times of soybean oversowing, occurring respectively, on 01/30/2006; (b) 02/13/2006; (c) 02/22/2006; and (d) 03/14/2006. Six cover crops were evaluated [ Brachiaria brizantha, B. ruziziensis, B. decumbes, Eleusine coracana, Pennisetum glaucum and cover crop-sorghum hybrid ( Sorghum bicolor cv. Bicolor) with Sudan-grass ( Sorghum bicolor cv. Sudanense)] and untreated (spontaneous vegetation) in four oversowing times. Oversowing was performed manually when the soybean reached the R 7 stadium (beginning of defoliation during physiological maturation), in each of the four sowing times of the 2005/06 soybean crop. The first cover crop desiccation was carried oat on 10/23/2006. After 20 days, the second desiccation was applied, followed by soybean sowing, cultivar MSOY 6101, early cycle, 0.45 m spaced, aimed at a population of 500.000 plants ha -1. Soybean oversowing, especially when using brachiaria, showed to be an important tool for the integrated management of weed plants, since it provides a larger biomass contribution and soil cover and sustainability to no-till systems in the cerrado.
  • Authors:
    • Sudhakar, S.
    • Ashish, P.
    • Panda, S.
    • Pandey, V.
  • Source: Environmental Geology
  • Volume: 56
  • Issue: 5
  • Year: 2009
  • Summary: An effort was made to identify the critical sub-watersheds for the development of best management plan for a small watershed of Eastern India using a hydrological model, namely, AVSWAT2000. A total of 180 combinations of various management treatments including crops (rice, maize, groundnut and soyabean), tillage (zero, conservation, field cultivator, mouldboard plough and conventional practices) and fertilizer levels (existing half of recommended and recommended) have been evaluated. The investigation revealed that rice cannot be replaced by other crops such as groundnut, maize, mung bean, sorghum and soyabean since comparatively these crops resulted in higher sediment yield. The tillage practices with disc plough have been found to have more impact on sediment yield and nutrient losses than conventional tillage practices for the existing level of fertilizer. Sediment yield decreased in the case of zero tillage, conservation tillage, field cultivator, mouldboard plough, and conservation tillage as compare to conventional tillage. Lowest NO 3-N loss was observed in zero tillage in all the fertilizer treatments, whereas field cultivator, mouldboard plough and disc plough resulted in increase of NO 3-N loss. As compared to conventional tillage, the losses of soluble phosphorus were increased in mouldboard plough. The losses of organic nitrogen were also increased as fertilizer dose increased. After zero tillage the conservation tillage performed better in all the fertilizer treatments as per loss of organic nitrogen and organic phosphorus is concerned. It can be concluded that the sediment yield was found to be the highest in the case of disc plough followed by mouldboard plough, field cultivator, conventional tillage, field cultivator and least in zero tillage practices. The nutrient losses were found to be in different order with tillage practices, resulted highest in disc plough tillage practices. In view of sediment yield and nutrient losses, the conservation tillage practice was found to be the best as the sediment yield is less than the average soil loss whereas nutrient loss is within the permissible limit.
  • Authors:
    • Oliveira, E.
    • Baliza, D.
    • Rodrigues, T.
    • Avila, F.
    • Faquin, V.
    • Rodrigues, C.
  • Source: CIENCIA E AGROTECNOLOGIA
  • Volume: 33
  • Issue: 6
  • Year: 2009
  • Summary: This study investigated the effect of the previous cultivation of different forage grasses fertilized with triple superphosphate (TSP) and reactive Arad phosphate (RAP) on growth, yield, and accumulation of P by soyabean. Two experiments were carried out: one in Haplic Cambisol typical distrophic, medium texture and the other in Red Latosol typical distrophic very clayey texture. For both experiments, the experimental design was a completely randomized one in a 4*2*2 factorial scheme; the previous crop being of four forage grasses utilized as cover plants in no-tillage system ( Brachiaria decumbens [Urochloa decumbens], Brachiaria brizantha [U. brizantha], millet and forage sorghum) fertilized with two sources of P (RAP and TSP) and two additional treatments, which are the cultivation of soyabean and bean plant without the previous growing of cover plants, and also fertilized with TSP and RAP. The plants were harvested after they had completed the development cycle. Grain and shoot dry matter yield and P accumulation in the shoot and in the grains of soyabean were determined. The forage plants immobilized the P of TSP, reducing the residual effect for soyabean. When forage grasses are fertilized with RAP, there is increased residual effect with increasing yield of soyabean in succession to the cover plants, with exception for the growing in succession to B. brizantha.
  • Authors:
    • Barbercheck, M. E.
    • Jabbour, R.
  • Source: Biological Control
  • Volume: 51
  • Issue: 3
  • Year: 2009
  • Summary: The growing demand for organic products creates opportunities for farmers. Information on the consequences of management practices can help farmers transition to organic and take advantage of these prospects. We examined the interaction between soil disturbance and initial cover crop on naturally occurring entomopathogenic fungi (EPF) during the 3-year transition to organic production in a feed grain rotation in central Pennsylvania. Our experiment included four systems comprised of a factorial combination of two levels of primary tillage (full vs. reduced) and two types of initial cover crop (timothy/clover vs. rye/vetch). The cropping sequence consisted of an initial cover crop, followed by soybean, and finally, maize. The entire experiment was replicated in time, with the initiation lagged by 1 year. We detected four species of EPF (Metarhizium anisopliae, Beauveria bassiana, Isaria fumosorosea, and Isaria farinosa) by bioassay of soil samples collected four times during each field season. The latter three species were detected infrequently; therefore, we focused statistical analysis on M. anisopliae. Detection of M. anisopliae varied across sampling date, year in crop sequence, and experimental start, with no consistent trend across the 3-year transition period. M. anisopliae was isolated more frequently in the systems initiated with timothy/clover cover crops and utilizing full tillage; however, we only observed a tillage effect in one temporal replicate. M. anisopliae detection was negatively associated with soil moisture, organic matter, and zinc, sulfur, and copper concentrations in the soil. This study helps to inform farmers about management effects on soil function, specifically conservation biological control. (C) 2009 Elsevier Inc. All rights reserved.