• Authors:
    • Leroux, X.
    • Attard, E.
    • Lemaire, G.
    • Laurent, F.
    • Chabbi, A.
    • Nicolardot, B.
    • Poly, F.
    • Recous, S.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia
  • Year: 2010
  • Summary: The COSMOS-Flux project aimed at studying two situations that have important environmental impacts at a larger scale : the conversion tillage no tillage where different tillage systems have been applied for 14 years at the start of experiment; the conversion grassland annual crop where the introduction of temporary grassland into rotations is studied. The characterization of upper layers of soil for C and N pools, mineralization, immobilization and nitrification of N, along with characteristics of the nitrifying and denitrifying bacterial communities (activity, size and structure) were followed during 18 to 36 months after conversion. We observed that the tillage of soils untilled for 14 years, or the ploughing of the 5-year old grassland were major disturbances for the soils, which led to a very fast evolution of soil organic matter pools, N fluxes and microbial activities towards the characteristics observed for tilled and arable situations. Conversely, the shifts from till to no-till, and the establishment of grassland on soil previously cropped with annual species did not change significantly their soil characteristics at the time scale of the study. Among soil environmental variables, soil organic carbon appeared as a key driver of the observed responses.
  • Authors:
    • Rensburg, L. D. van
  • Source: South African Journal of Plant and Soil
  • Volume: 27
  • Issue: 1
  • Year: 2010
  • Summary: This is the third soil physics review to be published in South African Journal of Plant and Soil. In the previous reviews the focus was broad and covered almost every aspect of the subject, providing a comprehensive list of contributions in soil physics. For the 25th year anniversary celebration of South African Journal of Plant and Soil, I have chosen to narrow the scope and focus on advances in soil physics in relation to irrigation and dryland agriculture. From a bio-physical viewpoint, South African researchers have made a major contribution to the body of scientific knowledge about irrigation and its application, expressed mainly in the form of irrigation or crop models such as PUTU, SWB and BEWAB. Attention was also given to modern ways of irrigation scheduling based on continuous soil water monitoring. Several irrigation scheduling service providers have adapted their businesses accordingly, with the result that South Africa is probably the leading country in Africa with respect to soil water monitoring and associated communication technology. In contrast, the review has shown that at farm and irrigation scheme level, salt management requires urgent attention. This is necessary as a precautionary measure to protect our natural resources. In the second part of the review the contribution of soil physics in relation to tillage practices is explored, and in particular how these have modified the field water balance components in order to enhance yield and rain water productivity. Based on the results of field experiments, new relationships were established, viz. rainfall and maize yield; water storage and yield; runoff and surface coverage by crop residue mulches; tillage depth, texture and yield relationships. Lastly, the review also showed how the water balance on clay and duplex soils in semi-arid zones can be modified through in-field rainwater harvesting to increase their rain water productivity. This technology has enhanced the livelihoods of many communal families who have applied the technique in their homesteads.
  • Authors:
    • Millen, J.
    • Evans, D.
    • Sadler, E.
    • Camp, C.
    • Stone, K.
  • Source: Applied Engineering in Agriculture
  • Volume: 26
  • Issue: 3
  • Year: 2010
  • Summary: Availability of spatially-indexed data and crop yield maps has caused increased interest in site-specific management of crop inputs, especially water and fertilizer As commercial equipment to implement site-specific applications of water and nutrients becomes available, crop response to variable inputs and decision support systems will be required to ensure profitable crop production while conserving natural resources and protecting the environment. The objective of this research was to determine corn yield response to a range of nitrogen fertilizer and irrigation amounts on a relatively uniform southeastern Coastal Plain soil under conservation tillage. Corn was grown in a field experiment using a center pivot irrigation system that had been modified to make site-specific applications of water and fertilizer during the period 1999-2001 on a site near Florence, South Carolina. Treatments included three antecedent crop rotations (prior four years), three irrigation regimes (0, 75%, and 150% of a base rate, IBR), and four nitrogen fertilizer amounts (50%, 75%, 100%, and 125% of a base rate, NBR), and with Put. replications. As expected, corn grain yields increased with irrigation and N fertilizer Mean corn grain yields for the three-year study ranged from 6.3 to 8.9 Mg/ha for the 0% IBR avail-twin, 9.4 to 10.5 Mg/ha for the 75% IBR treatment, and 10.0 to 10.6 Mg/ha for the 150% IBR treatment. The mean corn grain yields in response to N applications ranged from 6.4 to 8.0 Mg/ha for the 50% IBR treatment, 8.6 to 9.4 Mg/ha for the 75% NBR treatment, 9.1 to 10.9 Mg/ha for the 100% NBR treatment, and 8.8 to 11.7 for the 125% NBR treatment. However, the nature of the response varied among the three years, mainly because of differences in rainfall and rainfall distribution during the growing season. Also, during the first,year there was less response to N fertilizer (7.9 to 9.1 Mg/ha) possibly because of residual soil N from antecedent soybean crop. A regression analysis indicated that the slopes of the corn yield response to increased N fertilizer application were low for both irrigated and rainfed treatments in 1999. In both 2000 and 2001, the slopes were greater for the corn yield response to increased N fertilizer In 2000, the irrigated treatments had a greater slope of the yield response for additional N fertilizer than did the minted treatments. Using an orthogonal contrast analysis, the overall yield response for the combined irrigation treatments to N fertilizer was quadratic in 1999 and 2000, and linear in 2001. These quadratic yield response's indicated that, for these conditions, a potential upper limit on production for the applied N-fertilizer and water (rainfall and irrigation) was approached. For the minted treatment, yield response to N fertilizer was linear in all three years. These results provide useful information that should be helpful in developing management strategies and decision support systems for profitable management of both water and N fertilizer on spatially-variable soils in the southeastern Coastal Plain while conserving natural resources and protecting the environment.
  • Authors:
    • Molnar, L. J.
    • Blackshaw, R. E.
    • Moyer, J. R.
  • Source: Canadian Journal of Plant Science
  • Volume: 90
  • Issue: 4
  • Year: 2010
  • Summary: Farmers on the Canadian prairies are interested in including legume cover crops in their cropping systems to reduce fertilizer inputs and improve farm sustainability. A field study was conducted to determine the merits of establishing alfalfa ( Medicago sativa L.), red clover ( Trifolium pratense L.) or Austrian winter pea ( Pisum sativum L.) cover crops in fall or in spring with winter wheat ( Triticum aestivum L.). Spring-planted legumes emerged well within the winter wheat crop, but their growth was limited under these semi-arid conditions. Fall-planted red clover had low plant densities following winter in two of three experiments and fall-planted winter pea reduced winter wheat yield by 23 to 37% compared with the no cover crop control. In contrast, fall-planted alfalfa exhibited good winterhardiness, provided some weed suppression without reducing winter wheat yield, caused only a slight reduction in soil water content, and contributed an extra 18 to 20 kg ha -1 of available soil N at the time of seeding the following spring crop. Additionally, fall-planted alfalfa increased the yield of succeeding canola ( Brassica napus L.) in unfertilized plots in two of three experiments. Further research is warranted to better understand the agronomic and economic benefits of alfalfa-winter wheat intercrops under a wider range of environmental conditions.
  • Authors:
    • Karmakar, R.
    • Das, S. K.
    • Das, I.
  • Source: SATSA Mukhaptra Annual Technical Issue
  • Volume: 14
  • Year: 2010
  • Summary: In India, rice-wheat cropping system (RWCS) has contributed and will continue to contribute largely towards food security. Well-planned steps are necessary to make it sustainable and more productive without any adverse effects on the natural resources and the environment. Past studies indicate that sustainability of RWCS in the Indo-Gangetic Plains is at risk mainly due to decline in groundwater levels, soil organic matter content and nutrient availability, increased soil salinization and pest incidence. Practices for sustainable management diversified crop rotations that enhance soil cover and fertility, and accelarated adoption of resource conserving technologies like zero-tillage, bed planting, laser leveling, surface seeding, intercropping of high value crops, furrow irrigated raised bed planting technique, etc., all of which have been briefed in the present paper.
  • Authors:
    • Jasso-Chaverria, C.
    • Martinez-Gamino, M.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Symposium 3.2.1 Highland agriculture and conservation of soil and water
  • Year: 2010
  • Summary: Among the main constraints to adopting conservation tillage in the semiarid zones in Mexico's north-central region are: low acceptance among farmers, need of specialized machinery, use of herbicides, and above all, the need to utilize stubble to feed animals. The objective of this study was to assess the effect of different tillage methods in an irrigated corn-oat rotation system on corn grain, stubble, and forage oat yield. Seven tillage methods were evaluated: (1) traditional plow and disk (P+D), (2) disturbing the upper 0-4 in layer (D), (3) without disturbing the upper 0-4 in layer (ND), (4) zero tillage with 0% soil cover (ZT+0%SC), (5) zero tillage with 33% soil cover (ZT+33%SC), (6) zero tillage with 66% soil cover (ZT+66%SC), and (7) zero tillage with 100% soil cover (ZT+100%SC). In each year from 1996 to 2007, corn was sowed on the spring while forage oat was grown during the fall-winter season. Corn grain yield results showed statistical differences among treatments (p≤0.05), where ZT+66%SC was the best treatment, surpassing by 90% the corn yield registered with P+D. The statistical analysis for corn stubble yield showed no differences (p≥0.05) among treatments. With ZT+66%SC, corn stubble production was increased 3.448 ton/ha compared with that of P+D, indicating that farmers can use 2.0 ton ha -1 to cover at least 33% of the soil surface. Forage oat yields within the seven treatments were not statistically different ( P≥0.05), but all ZT treatments were no-till seeded. Our conclusions are that corn and forage oat can be no-till seeded, increasing corn production and keeping stable production of forage oat. These results can be used to provide evidence to farmers of the benefits of adopting conservation tillage.
  • Authors:
    • Muchaonyerwa, P.
    • Chiduza, C.
    • Murungu, F. S.
  • Source: African Journal of Agricultural Research
  • Volume: 5
  • Issue: 13
  • Year: 2010
  • Summary: Production of large biomass yields and weed suppression from cover crops have been major constraints affecting success and uptake of conservation agriculture technologies by smallholder irrigation farmers. A field study was undertaken to evaluate biomass accumulation and N uptake by oats ( Avena sativa), grazing vetch ( Vicia dasycarpa), faba bean ( Vicia faba), forage peas ( Pisum sativum) and Lupin ( Lupinus angustifolius) and their winter weed suppression efficacy in the 2007 and 2008 winter seasons. Cover crops were grown at two fertiliser levels: no fertiliser and fertilized. Control plots were included where no cover crop was grown. At the end of each winter season, glyphosate was applied to kill the cover crops and maize planted. Oats, grazing vetch and forage pea's cover crops produced mean dry weights of 13873, 8945.5 and 11073 kg ha -1 respectively while lupin had the lowest dry weight of 1226 kg ha -1. Oats responded to fertilisation while, there was little or no response from the other cover crops. Oats and grazing vetch also reduced weed density by 90 and 80% respectively while lupin only reduced weed density by 23% compared with the control plots. Grazing vetch fixed a mean of 112 kg N ha -1. The results suggest that legumes such as grazing vetch and forage peas may be grown to maximise biomass yields with minimal fertilizer inputs. Amount of biomass produced was a major factor in controlling winter weeds, while there was a progressive decline in the winter weed burden from the first to the second season. The low C:N ratio of grazing vetch (
  • Authors:
    • Wang, L.
    • Anjum, S.
    • Xue, L.
    • Zhang, Y,
    • Hu, X,
    • Wang, G.
    • Zou, C.
  • Source: Zhongguo Shengtai Nongye Xuebao / Chinese Journal of Eco-Agriculture
  • Volume: 18
  • Issue: 3
  • Year: 2010
  • Summary: Under the "wheat/maize/sweet potato" tri-crop intercropping system in the southwest China, we researched into the effects of different straw mulching treatments on root morphology, physiological characteristics of transplanted maize at seedling stage. Taking local traditional farming (T) as CK, the other two treatments were straw mulching (TS) and straw mulching plus decomposition catalysts (TSD). The entire experiment lasted for two years. Results show that straw mulching moderately increases root length and root surface area, while significantly increasing root length within 1.0-2.5 mm diameter compared with T treatment. However, there is no significant difference between TSD and TS treatments. Significantly increases in maize seedling root vigor by respectively 19.12%, 27.46%, in root-shoot ratio by 36.72%, 37.50%, and in root biomass by 62.53%, 69.42% are noted under TS and TSD treatments for 2008. Compared with T, the above indicators increase respectively by 17.86% and 25.83%, 31.54% and 33.08%, 65.69% and 77.37% for 2009. Meanwhile, straw mulching enhances soil moisture and nutrient supply. Straw mulching conservation tillage enhances root development and other physiological characteristics under maize intercropping system at seedling stage by changing farmland environment. Straw mulching with decomposition catalysts even performs better.
  • Authors:
    • Antle, J.
    • Ogle, S.
    • Paustian, K.
    • Basso, B.
    • Grace, P. R.
  • Source: Australian Journal of Soil Research
  • Volume: 48
  • Issue: 8
  • Year: 2010
  • Authors:
    • Ristolainen, A.
    • Sarikka, I.
    • Hurme, T.
    • Alakukku, L.
  • Source: Agricultural and Food Science
  • Volume: 19
  • Issue: 4
  • Year: 2010
  • Summary: Surface water ponding and crop hampering due to soil wetness was monitored in order to evaluate the effects of conservation tillage practices and perennial grass cover on soil infiltrability for five years in situ in gently sloping clayey fields. Thirteen experimental areas, each having three experimental fields, were established in southern Finland. The fields belonged to: autumn mouldboard ploughing (AP), conservation tillage (CT) and perennial grass in the crop rotation (PG). In the third year, direct drilled (DD) fields were established in five areas. Excluding PG, mainly spring cereals were grown in the fields. Location and surface area of ponded water (in the spring and autumn) as well as hampered crop growth (during June-July) were determined in each field by using GPS devices and GIS programs. Surface water ponding or crop hampering occurred when the amount of rainfall was clearly greater than the long-term average. The mean of the relative area of the ponded surface water, indicating the risk of surface runoff, and hampered crop growth was larger in the CT fields than in the AP fields. The differences between means were, however, not statistically significant. Complementary soil physical measurements are required to investigate the reasons for the repeated surface water ponding.