• Authors:
    • Anderson, R. L.
    • Liebig, M. A.
    • Krupinsky, J. M.
    • Hanson, J. D.
    • Tanaka, D. L.
    • Merrill, S. D.
  • Source: Agricultural Systems
  • Volume: 107
  • Year: 2012
  • Summary: The dynamic cropping systems concept proposes a long-term strategy of crop sequencing to achieve production, economic and soil care goals through sound ecological management. This requires that agriculturalists have comprehensive information about how crop species affect following years' crops. Little research exists about how differences in soil type and properties change crop sequence effects. Sandy loam, alluvial-derived soil in south central North Dakota, USA (400 mm/yr precipitation) was the site of a crop sequence experiment in which four species - maize ( Zea mays L.), dry pea ( Pisum sativum L.), spring wheat ( Triticum aestivum L.), and soybean ( Glycine max (L.) Merr.) - were grown in strips one year and in perpendicular strips the following, with spring wheat planted a third year. No-till management was used with three replications in land and two in time. Results were compared with those from two 10*10 sequence experiments on silt loam, glacial till-derived soil. Soil water depletion (SWD) and root growth were deeper in sandy loam soil than in silt loam. During a year of above average precipitation, prior year soybean enhanced spring wheat yield on sandy loam soil by 14% above average, but prior year spring wheat reduced it by 14%. During a year of deficient precipitation, prior crop effects on spring wheat yield ranked in order of expected springtime soil water storage: dry pea, 11%; spring wheat, 4%; soybean, -5%; maize, -10%. Prior crops' SWD largely determined spring soil water, with maize having greatest depletion. Excluding results from a year of low precipitation, prior crops' effects on spring wheat yield on sandy loam soil were similar to results found at two sequence experiments on silt loam soil: dry pea - generally positive effect (N-production, water conservation); spring wheat - negative (disease); soybean - positive (N-production); maize - generally negative (heavier water use). Same year comparison of three crops (nine sequences) on sandy loam soil vs. silt loam showed average dry pea and spring wheat yields being equivalent ( P<0.10). However, average maize yield was 37% lower on silt loam, with maize-after-maize yielding 54% less. The site with sandy loam land had topsoil with lower soil quality indicators (organic C, water holding capacity) than silt loam. However, no-till management and previous grass rendered productivity of the soils equivalent, and superior capacity of the sandy loam site subsoil to conduct water and be conducive to root growth lessened negative, water-generated crop sequence effects.
  • Authors:
    • Penha, L.
    • Khatounian, C.
    • Fonseca, I.
  • Source: Planta Daninha
  • Volume: 30
  • Issue: 1
  • Year: 2012
  • Summary: Weed control has always been an important issue in agriculture. With the advent of no-till systems, soil erosion was reduced but herbicide use was increased. Organic no-till systems try to adjust reduced erosion to the no use of herbicides. Nevertheless, this adjustment is limited by the cost of mechanical weed control. This cost may be reduced by improved cultural weed control with cover crops mulches. In this paper we report a study on the application of compost manure on an oats winter cover crop, preceding soybean, instead of on the soybean summer crop. Treatments comprised a control without compost manure, and compost manure doses of 4 and 8 Mg ha -1 applied either on oats in winter or soybean in summer, organized in a randomized block design, with five replications. In summer, plots were split into weed-controlled or not controlled subplots. The timing of application and the manure doses did not affect the oats biomass or the soybean performance. However, in summer, without water stress, the application of manure at 8 Mg ha -1 directly on soybean has reduced weed biomass in this crop.
  • Authors:
    • Seufert, V.
    • Ramankutty, N.
    • Foley, J. A.
  • Source: Nature
  • Volume: 485
  • Issue: 7397
  • Year: 2012
  • Summary: Numerous reports have emphasized the need for major changes in the global food system: agriculture must meet the twin challenge of feeding a growing population, with rising demand for meat and high-calorie diets, while simultaneously minimizing its global environmental impacts. Organic farming - a system aimed at producing food with minimal harm to ecosystems, animals or humans - is often proposed as a solution. However, critics argue that organic agriculture may have lower yields and would therefore need more land to produce the same amount of food as conventional farms, resulting in more widespread deforestation and biodiversity loss, and thus undermining the environmental benefits of organic practices. Here we use a comprehensive meta-analysis to examine the relative yield performance of organic and conventional farming systems globally. Our analysis of available data shows that, overall, organic yields are typically lower than conventional yields. But these yield differences are highly contextual, depending on system and site characteristics, and range from 5% lower organic yields (rain-fed legumes and perennials on weak-acidic to weak-alkaline soils), 13% lower yields (when best organic practices are used), to 34% lower yields (when the conventional and organic systems are most comparable). Under certain conditions - that is, with good management practices, particular crop types and growing conditions - organic systems can thus nearly match conventional yields, whereas under others it at present cannot. To establish organic agriculture as an important tool in sustainable food production, the factors limiting organic yields need to be more fully understood, alongside assessments of the many social, environmental and economic benefits of organic farming systems.
  • Authors:
    • Robertson, G.
    • Tausig, J.
    • Hamilton, S.
    • Basso, B.
    • Syswerda, S.
  • Source: Agricultural Ecosystems and Environment
  • Volume: 149
  • Year: 2012
  • Summary: Nitrate (NO 3-) loss from intensively farmed cropland is a long-standing, recalcitrant environmental problem that contributes to surface and groundwater pollution and coastal zone hypoxia. Here nitrate leaching losses are reported from nine replicated cropped and unmanaged ecosystems in southwest Michigan, USA. Ecosystems include four annual corn-soybean-winter wheat rotations under conventional, no-till, reduced-input, and organic/biologically-based management, two perennial cropping systems that include alfalfa and hybrid poplar trees, and three unmanaged successional communities including an early successional community analogous to a cellulosic biofuel system as well as a mature deciduous forest. The organic, alfalfa, and unmanaged systems received no synthetic, manure, or compost nitrogen. Measured nitrate concentrations were combined with modeled soil water drainage to provide estimates of nitrate lost by leaching over 11 years. Among annual crops, average nitrate losses differed significantly ( pno-till (41.33.0)>reduced-input (24.30.7) > organic (19.00.8) management. Among perennial and unmanaged ecosystems, nitrate loss followed the pattern alfalfa (12.81.8 kg N ha -1 yr -1)=deciduous forest (11.04.2) >> early successional (1.10.4)=mid-successional (0.90.4) > poplar (<0.010.007 kg N ha -1 yr -1) systems. Findings suggest that nitrate loss in annual row crops could be significantly mitigated by the adoption of no-till, cover crops, and greater reliance on biologically based inputs, and in biofuel systems by the production of cellulosic rather than grain-based feedstocks.
  • Authors:
    • Tessier, D.
    • Curmi, P.
    • Guimaraes, M.
    • Tavares Filho, J.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 1
  • Year: 2012
  • Summary: It is known that any kind of soil management causes changes in the soil physical characteristics and can affect agricultural yield. The purpose of this study was to evaluate soil properties of an Alfisol and soybean yield under different management systems for no-tillage annual crops, no-tillage with chiseling and no-tillage crop rotation. The 11-year experiment was initiated in the 1998/99 growing season, on 100*30 m plots (11% slope). Soil samples (5 per management system) were systematically collected (0-25 cm layer) in the summer growing season, to quantify soil organic matter, bulk density, macroporosity and flocculation, as well as soybean yield. The highest values for soil bulk density and organic matter content and the lowest for macroporosity were observed in the no-till system alone, whereas in the no-till system with quarterly chiseling the values for organic matter content were lowest, and no-tillage crop rotation resulted in the highest values for organic matter and macroporosity, and the lowest for soil bulk density. The average soybean yield was highest under no-till and trimestrial chiseling or crop rotation, and lowest for no-tillage annual crops no-tillage annual crops alone.
  • Authors:
    • Ugarte, D. G. de la T.
    • English, B. C.
    • Roberts, R. K.
    • Larson, J. A.
    • Toliver, D. K.
    • West, T. O.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 2
  • Year: 2012
  • Summary: This research evaluated differences in yields and associated downside risk from using no-till and tillage practices. Yields from 442 paired tillage experiments across the United States were evaluated with respect to six crops and environmental factors including geographic location, annual precipitation, soil texture, and time since conversion from tillage to no-till. Results indicated that mean yields for sorghum [ Sorghum bicolor (L.) Moench] and wheat ( Triticum aestivum L.) with no-till were greater than with tillage. In addition, no-till tended to produce similar or greater mean yields than tillage for crops grown on loamy soils in the Southern Seaboard and Mississippi Portal regions. A warmer and more humid climate and warmer soils in these regions relative to the Heartland, Basin and Range, and Fruitful Rim regions appear to favor no-till on loamy soils. With the exception of corn ( Zea mays L.) and cotton ( Gossypium hirsutum L.) in the Southern Seaboard region, no-till performed poorly on sandy soils. Crops grown in the Southern Seaboard were less likely to have lower no-till yields than tillage yields on loamy soils and thus had lower downside yield risk than other farm resource regions. Consistent with mean yield results, soybean [ Glycine max (L.) Merr.] and wheat grown on sandy soils in the Southern Seaboard region using no-till had larger downside yield risks than when produced with no-till on loamy soils. The key findings of this study support the hypothesis that soil and climate factors impact no-till yields relative to tillage yields and may be an important factor influencing risk and expected return and the adoption of the practice by farmers.
  • Authors:
    • Guimaraes, R. M. L.
    • Tormena, C. A.
    • Blainski, E.
    • Nanni, M. R.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 1
  • Year: 2012
  • Summary: Soil management strategies to improve and maintain soil physical quality (SPhQ) are essential for the sustainability of intensive agricultural systems. The least limiting water range (LLWR) is an indicator of SPhQ defined by the range of least restrictive soil water content to plants, i.e., a soil water content within the LLWR indicates an appropriate SPhQ for plants. In this context, soil mulching with crop residues can contribute to the SPhQ by increasing the frequency at which soil water availability is maintained within the LLWR (F within). The purpose of this study was to determine the LLWR of an Oxisol under no-tillage soybean and to evaluate F within under application of oat residue (0; 3; 6; 9; and 12 Mg ha -1) to the soil surface. An inverse relation of the LLWR with soil bulk density (Bd) was observed. With decreasing LLWR, F within decreased, independently of the oat residue rate. However, an increase in residue application increased the F within values, independent of the sampling position. The beneficial effect of the increase of residue amount on F within depended on the amplitude of the LLWR. With the increase of Bd and reduction of LLWR, higher residue amounts on the soil did not result in an increase of F within or of SPhQ, mainly when Db was close to the critical soil bulk density.
  • Authors:
    • Chapagain, T.
    • Riseman, A.
  • Source: American Journal of Plant Sciences
  • Volume: 3
  • Issue: 5
  • Year: 2012
  • Summary: A cultivar trial, including commercial and heirloom cultivars of major cereals and grain legumes was conducted in Vancouver, BC, under low input organic conditions. We assessed 19 wheat (6 commercial and 13 heirloom), 17 barley (8 commercial and 9 heirloom), 5 pea, 5 favabean, 5 kidneybean, 2 lentil, and 2 soyabean cultivars for plant performance metrics, and their potential in a small grain:legume intercropping system. Heirloom wheat cultivars showed notable response in a number of parameters including late maturity, taller plants, greatest number of spikes per m 2, longest spike, highest number of seed per spike, greater seed weight to volume ratio, and resistance to stripe rust compared with commercial cultivars. For the heirloom-type, 6 of 14 wheat cultivars, ( i.e., "Reward", "Glenn", "Cerebs", "Red Bobs", "Sounders" and "Black Bearded") produced yields comparable to the commercial cultivars ( i.e., nearly 5 t/h or higher). Also, heirloom cultivars typically contained higher protein levels most suitable for baking and blending purposes with "Einkorn" displaying the highest level (16.2%). Heirloom and commercial barley cultivars did not differ significantly with respect to plant height, spike length, and seed weight to volume ratio. However, a number of heirloom cultivars (e.g., "Jet", "Dolma", "Andie" and "Himalayan") displayed greater responses on earliness, number of spikes per m 2, grain yield, protein content and seed weight to volume ratio. Pea and lentil yielded lower than the national average under trial conditions. However, heirloom peas "Corgi", "De Grace", "Snowbird", and "Golden" were earlier compared to the commercial cultivar "Reward". All kidney bean cultivars yielded ~3 t/h with the highest yield from "Red Kidney" (3.8 t/h). Fava and soyabean appeared as promising crops as the cultivars produced good growth and yields. Neither lentil ("Crimson" and "Essex") produced satisfactory responses though they had excellent vegetative growth and flowered. Therefore, significant variation was observed including several heirloom cultivars displayed great potential in terms of yield, protein content, and disease resistance and that specific cultivars were better suited for an intercropping system.
  • Authors:
    • Pauletti, V.
    • Favaretto, N.
    • Molin, R.
    • Mellek, J. E.
    • Dieckow, J.
    • Da-Silva, V. L.
    • Vezzani, F. M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 3
  • Year: 2012
  • Summary: The quality of no-tillage systems depends on an adequate soil management that promotes soil structure improvements. This is associated to the cropping system adopted. This study investigated the effect of long-term no-tillage systems (18 years) on the structural quality of a sandy-clay to clay Oxisol (Latossolo Vermelho) in the region of Campos Gerais, Parana, Brazil. Five cropping systems were assessed: wheat-soybean [Wt-So], black oat-maize-wheat-soybean [Ot-Mz-Wt-So], vetch-maize-wheat-soybean [Vt-Mz-Wt-So], ryegrass-maize-ryegrass-soybean [Rg-Mz-Rg-So]; and alfalfa-maize [Alf-Mz]. Soil was sampled from the layers 0-5, 5-10 and 10-20 cm, in cylinders and in blocks with undisturbed structure. In the 0-5 cm layer, bulk density was lowest in the Ot-Mz-Wt-So (0.96 Mg m -3) and Vt-Mz-Wt-So systems (0.93 Mg m -3). In the 5-10 and 10-20 cm layers, the bulk density tended to be lowest in Alf-Mz systems (1.14 and 1.17 Mg m -3, respectively). A similar trend was observed for macroporosity, which in the top layer was greater in Ot-Mz-Wt-So (0.29 m 3 m -3) and Vt-Mz-Wt-So (0.30 m 3 m -3) and in the 5-10 and 10-20 cm layers tended to be greater in the Alf-Mz system (0.19 m 3 m -3). No clear trend was observed for microporosity. The saturated hydraulic conductivity was directly related with macroporosity, and was highest for Vt-Mz-Wt-So in the 0-5 cm layer (224 mm h -1) and Alf-Mz in the layers 5-10 (170 mm h -1) and 10-20 cm (147 mm h -1). In the Vt-Mz-Wt-So system, the mean weight diameter of aggregates was lowest in the 0-5 cm layer (2.39 mm) and highest (3.04 mm) in the Wt-So. The highest cone index values were observed in the Wt-So system, with over 1.5 MPa in the 7.5-22.5 cm layer. The compaction degree was lowest in the Alf-Mz system (0.2 MPa cm). Results were attributed mainly to the role of the crop roots of the systems and to the intensity of machinery traffic. Considering the 0-20 cm layer as a whole, the capacity to promote soil structural quality improvements was greater for the semi-perennial Alf-Mz system than for systems based on annual species. Bi-annual rotation systems, based on cover crops such as black oat and vetch, promote soil structural quality improvements compared to the wheat - soybean succession.
  • Authors:
    • Pannacci, E.
    • Onofri, A.
    • Graziani, F.
    • Tei, F.
    • Guiducci, M.
  • Source: European Journal of Agronomy
  • Volume: 39
  • Year: 2012
  • Summary: Long-term effects of organic (ORG) and conventional low-input (CONV) farming systems on size and composition of weed seedbank were assessed in 2007 in central Italy, in an on-farm experiment set up in 1996. In this experiment, six rotations (R1-R6) were considered, basically consisting on the same crop sequence with different starting points, i.e. (1) legume crop (soybean/field bean/common pea), (2) vegetable crop (pepper/melon), (3) winter cereal (soft/durum wheat), (4) summer cereal (maize) (5) industrial vegetable (processing tomato), (6) winter cereal (soft/durum wheat). All rotations were established both in ORG and in CONV, in strict adherence to EU regulations (ORG: EU reg. 2092/91; CONV: EU reg. 2078/92). Intercrops with green manuring purposes were included in ORG, while weed control was performed mechanically in ORG and chemically/mechanically in CONV. Weed seedbank was determined on 10 soil samples (0-0.30 m depth) in each plot and seeds were directly extracted, identified and counted. In all rotations, the adoption of ORG resulted in a significant increase in weed seedbank density, particularly in the case of summer weed species ( Portulaca oleracea L., Amaranthus retroflexus L. and Chenopodium album L.), which are more competitive and difficult to control in summer crops under organic farming systems in the Mediterranean climates. Small differences between ORG and CONV were found in terms of number of weed species (23 in ORG and 20 in CONV, on average), but the index of diversity in CONV was on average higher than in ORG. Furthermore, the most dominant weeds in CONV represented a lower percentage of total seedbank (40%, 23% and 5%, respectively, for P. oleracea, A. retroflexus and C. album in CONV and 56%, 32% and 4% for the same three weeds in ORG). These results confirm that the wider availability of effective weed control methods in integrated low-input farming systems (CONV) is helpful to maintain a low seedbank size, with a lower dominance structure. However, the adoption of ORG systems based on long rotation cycles, very competitive crops and accurate weed control, especially at the beginning of the ORG management, may be sustainable in the long run, in terms of potential weed infestation levels.