41. Climate change and water security: Estimating the greenhouse gas costs of achieving water security through investments in modern irrigation technology

• Authors:
  • Reardon-Smith, K.
  • Maraseni, T. N.
  • Mushtaq, S.
• Source: Agricultural Systems
• Volume: 117
• Year: 2013
• Summary: There are significant concerns about the longer term impact of climate change and climate variability on water availability in Australia. Modern irrigation technologies are seen as a way to manage climate change impacts and improve water security. However, while modern irrigation technologies may save volumes of water, it is likely that they will result in increased on-farm energy consumption and greenhouse gas (GHG) emissions, suggesting potential conflicts in terms of mitigation and adaptation policies. Five irrigation technology transformation scenarios-three historical and two adoption-were developed to evaluate industry-wide tradeoffs between water savings, energy consumption (and GHG emissions), and economic returns associated with irrigation technology transformations under current Australian Government water resource policies. Three of the five scenarios tested showed tradeoffs between water savings and GHG emissions, with water savings through conversion of irrigation systems increasing both energy consumption and GHG emissions. For example, 120 GL/year of water savings achieved through drip irrigation adoption for cotton cropping would increase energy consumption by 889 TJ/year and GHG emissions by 250,000 t CO(2)e/year. A carbon price of $20/t CO(2)e would result in additional costs nationally of about $5 m/year. However, this study also indicated that significant benefit in terms of water savings and GHG reduction can be achieved when replacing older inefficient and energy-intensive systems, such as hand shift and roll-line sprinkler systems, especially when these are replaced with drip irrigation systems. We suggest priority should be given to replacing such systems while implementing the on-farm infrastructure investment policy. The findings of the study support the use of an integrated approach to avoid possible conflicts in designing national climate change mitigation and adaptation policies, both of which are being developed in Australia.

42. A scan level cotton carbon life cycle assessment: has bio-tech reduced the carbon emissions from cotton production in the USA?

• Authors:
  • Teague, T. G.
  • Niederman, Z.
  • Danforth, D. M.
  • Nalley, L. L.
• Source: Journal of Cotton Science
• Volume: 17
• Issue: 2
• Year: 2013
• Summary: Greenhouse gas (GHG) emissions are a growing concern for agricultural producers given increased pressure from government, consumers and retail purchasers. This study addresses the changes in greenhouse gas emissions in cotton over time (using years 1997, 2005 and 2008) due to changing production methods including tillage and seed technology. Time series data in this study comes from a single farm in Arkansas with detailed records of seed used, all inputs used (e.g. fertilizers, agrochemicals, irrigation), as well as machinery and tillage type for each of over 121 fields over 11 growing seasons. Results indicate yields increased dramatically (68%) over that time, due primarily to seed technology. At the same time, agrochemical use and fuel use decreased in 2008, primarily due to Bollgard II Roundup Ready Flex seed technology and the resulting reduced tillage. Reduced inputs can result in lower costs for producers, as well as reduced greenhouse gas emissions. Increasing yields with reduction in input use reduces the overall greenhouse gas emissions per pound of cotton produced, resulting in benefits to producers, consumers who demand such traits, and the environment. However, due to the proliferation of glyphosate-resistant pigweed ( Amaranthus palmeri), the decreases in greenhouse gas emissions per pound of cotton that were observed over the past decade may be reversed.

43. Conservation tillage for organic agriculture: evolution toward hybrid systems in the western USA.

• Authors:
  • Luna, J. M.
  • Mitchell, J. P.
  • Shrestha, A.
• Source: Renewable Agriculture and Food Systems
• Volume: 27
• Issue: 1
• Year: 2012
• Summary: Organic farming has been historically dependent on conventional tillage operations to convert perennial pasture leys to annual crop rotations, incorporate crop residues, compost and cover crops, as well as to mechanically kill existing vegetation. Conventional tillage, however, has long been known to lead to soil degradation and erosion. A recently developed no-till organic production system that uses a roller-crimper technology to mechanically kill cover crops was evaluated in two states in the western United States. In Washington, pumpkins ( Cucurbita spp.) grown in a no-till roller-crimper (NT-RC) system produced yields 80% of conventional tillage, but with fewer weeds. However, in California on-farm research trials in organic cotton ( Gossypium barbadense L.), tomato ( Lycopersicon esculentum Mill.), eggplant ( Solanum melongena L.) and cowpea ( Vigna unguiculata (L.) Walp.), the no-till system produced virtual crop failure, or yields less than 20% of the standard production method. The major problems associated with rolled cover crops in California included reduced crop seedling emergence, planter impediment with excessive residue, lack of moisture and delay in transplanting of vegetable crops due to continued growth of cover crops, in-season crop competition from cover crop regrowth and impracticability of using cultivators. Further, excessive dry residue during summer in California can present the risk of fire. In both California and Oregon, considerable success has been demonstrated with zone tillage (strip tillage) in conventionally produced field and vegetable crops. In a replicated Oregon trial, the organic strip tillage treatment produced 85% of the broccoli ( Brassica oleracea L.) yield compared to a conventional tillage treatment. Our studies suggest that the zone tillage concept may offer opportunities to overcome many of the agronomic challenges facing no-till.

44. Carbohydrate composition and water-stable aggregation of an oxisol as affected by crop sequence under no-till

• Authors:
  • Martins, M. dos R.
  • Angers, D. A.
  • Cora, J. E.
• Source: Soil Science Society of America Journal
• Volume: 76
• Issue: 2
• Year: 2012
• Summary: In no-till systems, plants play a substantial role in soil physical conditioning because physical management is otherwise confined to sowing operations. We performed a study to determine the effect of 28 different crop sequences on soil water-stable aggregation, soil organic C (SOC), and the neutral carbohydrate composition of the surface layer (0-5-cm depth) of an Oxisol under no-till. Summer crop sequences with corn ( Zea mays L.) on a continuous basis or in rotation with soybean [ Glycine max (L.) Merr.] showed a higher mean weight diameter (MWD) of water-stable aggregates than those with a rice ( Oryza sativa L.)-bean ( Phaseolus vulgaris L.)-cotton ( Gossypium hirsutum L.) rotation. Among winter crops, pearl millet [ Pennisetum americanum (L.) Leeke] or grain sorghum [ Sorghum bicolor (L.) Moench] were associated with a higher MWD than oilseed radish ( Raphanus sativus L. var. oleiformis Pers.). Plant tissues of Poaceae species (corn, pearl millet, and sorghum) were enriched in pentoses relative to other plant species. A principal component analysis showed a close positive relationship of the soil aggregate MWD with the soil xylose content, but not with other soil monosaccharide and SOC contents, and a positive relationship with the amount of pentose input to the soil, notably from aboveground plant materials. A possible explanation is that pentosans are used as an energy source by filamentous microorganisms, which play a well-known role in stabilizing soil aggregates. Our results suggest that plant-derived carbohydrates mediate crop species effects on soil structure under no-till conditions, and this effect appears to be independent of changes in total SOC.

45. Nitrogen Uptake Pattern by Cotton in a Long-term No-tillage System with Poultry Litter Application

• Authors:
  • Nyakatawa, E. Z.
  • Reddy, S. S.
  • Reddy, C. K.
• Source: International Journal of Agriculture & Biology
• Volume: 14
• Issue: 1
• Year: 2012
• Summary: Nitrogen uptake pattern by cotton (Gossypium hirsutum L.) at different growth stages in response to long-term application of poultry litter (PL) in a no-till system (NT) was studied on a silt loam soil in 2009. The study was done in plots that were established in 1996 at TVREC, Belle Mina, AL, USA. Treatments included were three tillage [conventional tillage (CT), mulch-tillage (MT), and no-tillage (NT)] two cropping systems tot ton-lye (C-R; cotton in summer & cereal rye cover crop in winter), and cotton-fallow (C-F; cotton in summer & fallow in winter)] and two sources of nitrogen [PL at 100 and 200 kg N ha(-1) and ammonium nitrate (AN) at 100 kg N ha(-1)] Out of all treatment combinations only 11 important treatments were selected and arranged in a randomized complete block design and replicated 4 times. Results in 2009, showed that NT system can supply equal quantity of nitrogen compared to CT at all growth stages. No-tillage recorded similar growth, yield and total nitrogen uptake compared to CT. Application of PL at 100 kg N ha(-1) showed significantly superior plant growth compared to AN at early growth stage, but the differences disappeared as the plant growth progressed. Similar yields and nitrogen uptake were observed with application of either PL or AN at 100 kg N ha(-1). Application of a double rate of PL (200 kg N ha(-1)) resulted in significantly higher nitrogen uptake compared to that of PL or AN at 100 kg N ha(-1), but a significant yield advantage was not observed with this higher rate. Of the total nitrogen extracted by cotton at maturity, 50% uptake was completed by early flowering stage and 97% was completed by boll development stage. At maturity, the majority of nitrogen (52%) was partitioned into seeds, while the rest was distributed into leaves (16%), stems (18%) and reproductive parts (14%). winter rye cover crop did not influence nitrogen uptake. (C) 2012 Friends Science Publishers

46. Soil moisture distribution and root characters as influenced by deficit irrigation through drip system in cotton-maize cropping sequence.

• Authors:
  • Sampathkumar, T.
  • Pandian, B. J.
  • Mahimairaja, S.
• Source: Agricultural Water Management
• Volume: 103
• Year: 2012
• Summary: Field experiments were conducted during 2007-2009 to study the effect of deficit irrigation practices through drip irrigation system on soil moisture distribution and root growth in cotton-maize cropping sequence. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through ADI practice in paired row system of drip layout, that is commonly practiced in India. In the present study, PRD and deficit irrigation (DI) concepts (creation of soil moisture gradient) were implemented through alternate deficit irrigation (ADI) at two levels of irrigation using drip system. Experimental treatments comprised of six irrigation levels (full and deficit) through drip system with surface irrigation for comparison. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Roots confined to the shallow depth and recorded the lowest values for both the crops under conventional drip irrigation at 100% ETc. Among the deficit irrigation treatments, mild deficit irrigation produced longer lateral roots from both the sides of the plant. Contrary to rooting depth, severe water stress affected the lateral root spread and recorded lower values than other drip irrigation treatments. Soil moisture content (SMC) was low nearer to the plant (at 30 cm across the lateral) and far away (at 30 cm along the lateral) from the plant, irrespective of treatments. The reduction in SMC was increased at all locations as applied water level decreased. It is concluded that alternate watering imposed through ADI at 100% ETc produced longer lateral roots with higher values for root dry mass Alternate deficit irrigation (ADI) resulted uneven distribution of soil moisture content. Among the ADI treatments, ADI at 100% had less uneven distribution than ADI at 80% ETc.

47. Effects of no-till on yields as influenced by crop and environmental factors.

• 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.

48. Cover crops and nitrogen application on cotton.; Plantas de cobertura e adubacao nitrogenada na cultura do algodoeiro.

• Authors:
  • Ferrari, J. V.
  • Furlani Junior, E.
  • Ferrari, S.
  • Alberton, J. V.
• Source: Revista Brasileira de Ciencias Agrarias
• Volume: 7
• Issue: 2
• Year: 2012
• Summary: The fiber quality, productivity and favorable climate are considered key points for the development of the cotton crop in the Brazilian Cerrado. This study aimed to evaluate the effect of cover crops and N application in pre-sowing on the cotton crop growth and yield. The experimental design was randomized blocks, consisting of a - three cover crops (radish, white oat and black oat) implanted during the winter period, b - four nitrogen levels (0, 30, 60 and 90 kg ha -1 of N) applied to the millet residues and before cotton sowing. In April 2008, evaluations were realized of plant development and also harvesting was performed of experimental plots of cotton plants. The results showed that the radish provides increased length of branches and cotton bolls of cotton crop, without yield increase, and the use of increasing doses of N up to 90 kg ha -1 decreased the amount of carima per plant, increasing the number of reproductive branches and cotton yield.

49. Evaluating greenhouse gas emissions inventories for agricultural burning using satellite observations of active fires.

• Authors:
  • Randerson, J.
  • Foley, J.
  • Giglio, L.
  • Jin, Y.
  • Lin, H.
• Source: Ecological Applications
• Volume: 22
• Issue: 4
• Year: 2012
• Summary: Fires in agricultural ecosystems emit greenhouse gases and aerosols that influence climate on multiple spatial and temporal scales. Annex 1 countries of the United Nations Framework Convention on Climate Change (UNFCCC), many of which ratified the Kyoto Protocol, are required to report emissions of CH 4 and N 2O from these fires annually. In this study, we evaluated several aspects of this reporting system, including the optimality of the crops targeted by the UNFCCC globally and within Annex 1 countries, and the consistency of emissions inventories among different countries. We also evaluated the success of individual countries in capturing interannual variability and long-term trends in agricultural fire activity. In our approach, we combined global high-resolution maps of crop harvest area and production, derived from satellite maps and ground-based census data, with Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) measurements of active fires. At a global scale, we found that adding ground nuts (e.g., peanuts), cocoa, cotton and oil palm, and removing potato, oats, rye, and pulse other from the list of 14 crops targeted by the UNFCCC increased the percentage of active fires covered by the reporting system by 9%. Optimization led to a different recommended list for Annex 1 countries, requiring the addition of sunflower, cotton, rapeseed, and alfalfa and the removal of beans, sugarcane, pulse others, and tuber-root others. Extending emissions reporting to all Annex 1 countries (from the current set of 19 countries) would increase the efficacy of the reporting system from 6% to 15%, and further including several non-Annex 1 countries (Argentina, Brazil, China, India, Indonesia, Thailand, Kazakhstan, Mexico, and Nigeria) would capture over 55% of active fires in croplands worldwide. Analyses of interannual trends from the United States and Australia showed the importance of both intensity of fire use and crop production in controlling year-to-year variations in agricultural fire emissions. Remote sensing provides an effective means for evaluating some aspects of the current UNFCCC emissions reporting system; and, if combined with census data, field experiments and expert opinion, has the potential to improve the robustness of the next generation inventory system.

50. Special issue: Advances in irrigation.

• Authors:
  • [Anonymous]
• Source: Applied Engineering in Agriculture
• Volume: 28
• Issue: 3
• Year: 2012
• Summary: This special section includes four papers providing information on the: current status of microsprinkler irrigation in the USA; cotton response to crop row offset and orientation to subsurface drip irrigation laterals; integrated decision support, sensor networks, and adaptive control for wireless site-specific sprinkler irrigation; and a review of mechanical move sprinkler irrigation control and automation technologies.