• Authors:
    • Nelson, K. A.
    • Udawatta, R. P.
    • Motavalli, P. P.
    • Bailey, N. J.
  • Source: Agroforestry Systems
  • Volume: 77
  • Issue: 2
  • Year: 2009
  • Summary: The potential for agricultural soils to act as a sink and sequester carbon (C) or a source and emit carbon dioxide (CO2) is largely dependent upon the agricultural management system. The establishment of permanent vegetation, such as trees and grass contour buffer strips, may cause accumulation of above- and below-ground C over time, thereby acting as a sink for tropospheric CO2. However, the effects of contour grass strips and grass-tree strips (agroforestry) on soil CO2 emissions have not been extensively studied in row-crop watersheds in the temperate regions. The objective of this study was to determine the effects of agroforestry and grass contour buffer strips and landscape position on soil surface efflux rate of CO2 in three adjacent agricultural watersheds with claypan soils in northeast Missouri. The three watersheds were in a corn-soybean rotation, and contained (1) cropped only (CR), (2) cropped with grass contour strips (GR), or (3) cropped with tree-grass contour strips (AF) management systems. Soil surface CO2 efflux was measured throughout the 2004 growing season at the upper (UBS), middle (MBS), and lower (LBS) backslope landscape positions within the three watersheds. The cumulative soil CO2 production was lowest in the CR (0.9 kg CO2-C m-2) compared to the AF (1.5 kg CO2-C m-2) and GR watersheds (1.5 kg CO2-C m-2). The lower backslope position (1.6 kg CO2-C m-2) across all three watersheds produced 32 and 40% greater cumulative soil CO2 than the upper and middle backslope positions, respectively. A 72-day incubation study determined the effects of 40, 60, 80, and 100% soil water-filled pore space (WFPS) and N rate (0 and 1.39 g KNO3 kg soil-1) on soil CO2 efflux from bulk soil collected under each management system. The cumulative CO2 production was highest in the grass soil (1,279 mg CO2-C kg soil-1) compared to the agroforestry (661 mg CO2-C kg soil-1) and cropped (483 mg CO2-C kg soil-1) soils regardless of WFPS and N rate. The highest cumulative CO2 production for the grass soil (1,279 mg CO2-C kg soil-1) occurred at 80% WFPS, and was approximately 2 to 2.6 times greater than the agroforestry and cropped soils at 80% WFPS. The results of this study indicate that conservation management practices, such as grass and grass-tree contour buffer strips, and landscape position affect soil surface CO2 production and accumulation of soil organic C that may influence soil C sequestration.
  • Authors:
    • Benbrook, C.
  • Source: Critical Issue Report: The First Thirteen Years
  • Year: 2009
  • Summary: Th is report explores the impact of the adoption of genetically engineered (GE) corn, soybean, and cotton on pesticide use in the United States, drawing principally on data from the United States Department of Agriculture. Th e most striking finding is that GE crops have been responsible for an increase of 383 million pounds of herbicide use in the U.S. over the first 13 years of commercial use of GE crops (1996-2008).
  • Authors:
    • Lal, R.
    • Blanco-Canqui, H.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Franzluebbers (2009) is right about the need for a more intensive soil sampling, "repeated sampling with time,"and "stratified sampling" as well as for the use of multiple fields and collection of larger number of pseudoreplicates to overcome the high field variability in soil organic carbon (SOC) pools within each Major Land Resource Area (MLRA). The selected fields were representative of each MLRA in terms of soil type, slope, and management, but it is correct that a single soil would not capture all the variability in soil and management for the whole MLRA. This study was not intended to relate the data from the single soil to the whole MLRA but rather to emphasize the differences in SOC sequestration rates among the three management systems within each soil.
  • Authors:
    • Urquiaga, S.
    • Alves, B. J. R.
    • Jantalia, C. P.
    • Boddey, R. M.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Blanco-Canqui and Lal (2008) present data on soil organic carbon (SOC) concentrations from soils managed under no-tillage (NT) or plow-tillage (PT) from samples taken from studies of paired fields at 11 (MLRA) sites in three states of the USA. The results seem to show extremely large annual changes in soil organic C stocks between NT and PT to a depth of 60 cm, ranging from +3.75 to -6.65 Mg ha-1 yr-1 (Table 2). However, these values are far greater, and not compatible with, the data displayed in Fig. 2, nor the total stocks of soil N and the C/ N ratio displayed in Tables 3 and 4, respectively. However, the data displayed taken from seven studies in the literature (a total of 16 comparisons) are correctly reported as annual changes. Table 2 should thus be corrected as shown here (Table 1).
  • Authors:
    • Ren, C.
    • Ma, B.
    • Zhao, G.
  • Source: Crop Science
  • Volume: 49
  • Issue: 3
  • Year: 2009
  • Summary: Nitrogen uptake and partitioning in oat ( Avena sativa L.) are not well documented. A greenhouse study was conducted to determine the critical timing of N supply on the growth, N uptake, and partitioning. Plants grown in plastic pots were subjected to five N fertilization regimes: (i) control, N supply from seedling to physiological maturity (PM); (ii) N supply from seedling to flag leaf; (iii) N supply from flag leaf to PM; (iv) N supply from seedling to heading; and (v) N supply from heading to PM. Leaf chlorophyll content, plant dry matter (DM), and N uptake and accumulation were measured. Total plant DM was 21% greater for naked 'VAO-2' than for covered 'Prescott', while both genotypes produced similar grain yields. Varietal differences in total plant N were significant ( P
  • Authors:
    • Meera, P.
    • Pandey, A.
    • Amarnath, S.
  • Source: Environment and Ecology
  • Volume: 27
  • Issue: 3A
  • Year: 2009
  • Summary: A field experiment was conducted during three consecutive years of 2000-01 to 2002-03 to study the nutrient management on yield, quality and fertility status in tobacco based intercropping system in North Bihar. Results revealed that significantly highest cured and first grade leaf yield of tobacco was obtained in tobacco+garlic than other intercropping systems. Highest net and gross return and cost: benefit ratio were realized in tobacco+garlic followed by tobacco+rajmash and tobacco+potato intercropping systems. Application of 100% recommended dose of fertilizers (RDF) produced significantly highest cured and first grade leaf yield of tobacco as compared to rest of the fertility levels. Application of 100% RDF registered more gross and net returns and cost: benefit ratio. The physical parameters of maturity score was recorded more in tobacco+garlic intercropping and application of 100% RDF. Physical and chemical compositions of soil after harvest of tobacco was restored more in 100% RDF along with tobacco+garlic intercropping.
  • Authors:
    • Cadet, P.
    • Spaull, V.
    • Dana, P.
    • Berry, S.
  • Source: Nematropica
  • Volume: 39
  • Issue: 1
  • Year: 2009
  • Summary: Two trials were planted on sandy soils on small-scale grower farms to study the effect of intercropping on the nematode fauna, soil and plant fertility and sugarcane yield. Peanut ( Arachis hypogaea) and sugar bean ( Phaseolus limensis) were intercropped between the sugarcane rows in the first trial; velvet bean ( Mucuna deeringiana) and sweet potato ( Ipomoea batatas) were intercropped in the second trial. These practices were compared to a standard aldicarb (nematicide) treatment and an untreated control. In the first trial (irrigated sugarcane), peanut grew well as an intercrop, however, 70% of the sugar bean died before producing seeds. Intercropping with sugar bean had no effect on initial sugarcane stalk number whereas peanut reduced initial sugarcane stalk number by 30%. In the second trial (non-irrigated sugarcane), both velvet bean and sweet potato grew well as intercrops. Intercropping resulted in initial reduction in sugarcane stalk number of 30% for sweet potato and 70% for velvet bean. However, for both trials, and for all intercrops (except peanut), the sugarcane stalk number at harvest was the same as that of the control. Intercropping with velvet bean, peanut and sweet potato increased Meloidogyne javanica and Pratylenchus zeae infestation of the sugarcane sett roots; conversely, intercropping with sugar bean reduced nematode infestation. Intercropping with velvet bean, sugar bean and sweet potato had no effect on sugarcane yield, whereas intercropping with peanut reduced sugarcane yield by 22% and sucrose yield by 29%. Intercropping with velvet bean increased levels of some nutrients in the soil and leaves of sugarcane. These results show that intercropping can be used by small-scale growers to: manage nematodes (sugar bean), provide nutrients to the sugarcane crop (velvet bean), provide alternative food source and/or income (sweet potatoes) and to improve the overall productivity of the land without being detrimental to sugarcane cultivation.
  • 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:
    • Govindakrishnan, P.
    • Lal, S.
    • Dua, V.
  • Source: Indian Journal of Agricultural Sciences
  • Volume: 79
  • Issue: 5
  • Year: 2009
  • Summary: A field experiment was conducted at Shimla, Himachal Pradesh, India, during 2003-06, to determine the nutrient requirement of French bean ( Phaseolus vulgaris) when intercropped with potato ( Solanum tuberosum) under 2:2 row ratio in which 2 rows of French bean (paired at 30 cm) were planted at 2 population densities (88 888 plants/ha with 15 cm plant spacing and 133 333 plants/ha with 10 cm plant spacing) after every 2 rows of potato planted at 50 cm. Potato tuber yield was not affected since it was supplied with a uniform recommended dose of NPK and farmyard manure in all the treatments. Results revealed that in the potato+French bean (2:2) intercropping, French bean required only 2/3 of the recommended NPK and farmyard manure, applied on the basis of their sole crop density in intercropping, irrespective of its planting spacing. The increase in pod yield of French bean under this treatment over control was 1.62 tonnes/ha (38.7%) and 1.78 tonnes/ha (37.0%) at population densities of 88 888 and 133 333 plants/ha, respectively. At this level of fertility, French bean with 133 333 plants/ha gave 13.4% more pods (0.78 tonnes/ha) than with 88 888 plants/ha. The nutrient balance was also positive as the removal of N, P and K was 40.6, 31.2 and 44.1%, respectively, with 88 888 plants/ha of French bean and 39.3, 27.1 and 42.7%, respectively, with 133 333 plants/ha of Frenchbean grown with 2/3 of recommended NPK+farmyard manure. The economics was also favourable for these treatments.
  • 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.