Low Greenhouse Gas Agriculture: Mitigation and Adaptation Potential of Sustainable Farming Systems

Is low greenhouse gas emission (GHG) agriculture possible? Is it, in fact, desirable? In seeking answers to these two basic but extremely relevant questions, this study examines current farming practices, and incorporates scientific databases from longterm field experiments as case studies for low GHG agriculture. Further, the study examines the changes that will be needed for low greenhouse gas agriculture systems to become a reality. It also elucidates the adaptive capacity of agro-ecological farming system approaches, using organic system case studies from the scientific literature. Each year, agriculture emits 10 to 12 percent of the total estimated GHG emissions, some 5.1 to 6.1 Gt CO2 equivalents per year. Smith, et al. (2007) and Bellarby, et al. (2008) have proposed mitigation options for GHG emissions, finding that both farmers and policymakers will face challenges from the GHG-related changes needed in agriculture. Areas for improvement include increased use of no-till cropping, agro-forestry, and integrated crop and animal farming, and decreased use of external inputs in food and agriculture. The techniques offered by organic agriculture are valuable for consideration in these efforts

Impacts of Organic and Conventional Management on the Nutritional Level of Vegetables

The nutrient concentration of fruits and vegetables in the U.S.A. has declined in the past 50–70 years. Crop management practices utilizing on-farm inputs are thought to increase crop nutritional quality, but few studies have evaluated this under long-term side-by-side trials. An experiment was conducted from 2004 to 2005 at Rodale Institute’s long-term Farming Systems Trial to investigate the nutritional quality of vegetables under organic manure (MNR) and conventional (CNV) farming systems, with or without arbuscular mycorrhizal fungi (AMF) treatment. AMF reduced the vitamin C content in carrots in both systems in 2004, but the reduction was 87% in CNV and 28% in MNR. AMF also reduced antioxidants in carrots in both CNV and MNR. This trend was likely due to the suppression of native AMF colonization by the non-native AMF inoculum used. Between 2004 and 2005, MNR increased the vitamin C in green peppers by 50% while CNV decreased the vitamin C in red peppers by 48%. Tomatoes under MNR had a 40% greater vitamin C content compared to CNV in 2005. The vegetable yield declined between 2004 and 2005, except for tomato, where the yield increased by 51% and 44% under CNV and MNR, respectively. In general, MNR tended to increase the nutrient concentration of vegetables compared with CNV, while the AMF effects were inconclusive

Does Organic Farming have Greater Potential to Adapt to Climate Change?

Agricultural production in most parts of the world will face less predictable weather conditions than mankind experienced during the intensification of agriculture over the last century. Especially South Asia and Southern Africa could suffer negative impact on several crops when no investments will be made into improved adaptiveness of the production systems. Besides specific technical measures (irrigation, breeding for drought improved or heat tolerant crops), the resilience of whole production systems is a very important focus. Organic agriculture is a highly knowledge-based technique for manipulating complex agro-ecosystems, for breeding locally adjusted seeds and livestock, and for producing on-farm fertilizers and inexpensive nature-derived pesticides. Such knowledge is a crucial ‘reservoir of adaptations’. Soil fertility-building and soil conserving techniques bring organic farming in a good position to maintain productivity in the event of drought, irregular rainfall events with floods, and rising temperatures. Such techniques are i) the on-farm flux of manure from livestock production to cropland, ii) the use of composts, iii) the use of leguminous crops and green manure in rotations, iv) diversified crop sequences with permanent soil cover and different rooting depths as well as v) minimum or shallow tillage. Although organic agriculture is not designed to use water as efficient as possible, different agricultural techniques used in organic agriculture effect water use efficiency of organic arable crops in a positive way. In addition, organic management practices also decrease pollution in water effluent as the main pollutants like mineral nitrogen and pesticides are banned. An additional strength of organic farming systems is their diversity – including the diversity of crops, fields, rotations, landscapes and farm activities. The high level of diversity of organic farms provides many ecological services that significantly enhance farm resilience. Positive effects of enhanced biodiversity on pest and disease as well as on better utilization of soil nutrients and water prevention are well documented. Genetic diversity of crops is generally considered a fundamental resource for adaptation and therefore crucial for the stability of food supply. As resilience and robustness to environmental stress are multigenetic characteristics, the in situ conservation and on-farm breeding are likely to be more successful than genetic engineering. There are many initiatives by plant and animal breeders in the context of organic farms. To conclude, organic agriculture is a productive agro-ecosystem which might be very resilient and adaptive to climate change scenarios

Título en español

Más del 90% de las aislaciones de Fusarium en semillas de soya 'Davis' cosechadas en Corozal e lsabela, Puerto Rico, se identificaron como F. semitectum; 3 y 2% de las mismas aislaciones se identificaron como F. oxysporum y F. solani, respectivamente; y menos de 1% como F. rigidusculum y F. episphaeria var. dimerum. La incidencia de F. semitectum lleg6 a 32.6% de todas las aislaciones de hongos en Corozal y 24.8% en Isabela. Se encontraron las primeras infecciones internas en semillas de soya 'Improved Pelican' cuando las vainas estaban hechas pero todavía verdes. La incidencia de infección en la semilla aumentó notablemente en vainas amarillas y en etapas más avanzadas. Vainas hechas pero verdes se cosecharon e inocularon con F. semitectum. Se notaron pérdidas en la viabilidad de la semilla cuando las vainas inoculadas se incubaron par 5 días a 95% HR y 27° C. Las semillas de las vainas inoculadas perdieron 65% de su viabilidad mientras que las de las vainas inoculadas sobre heridas artificiales perdieron la viabilidad totalmente. El barrenador de la vaina de la haba (Etiella zinckenella) aumentó la infección de semillas por F. semitectum y disminuyó la germinación y la infección por Phomopsis sp. En vainas abortadas se observó una elevada incidencia (85%) de F. semitectum. Collectotrichum dematium, Phomopsis sp., Botryodiploidia theobromae y Alternaria tenuissima tambien colonizaron las vainas abortadas, pero a incidencias menores de 8% cada uno.</jats:p

Comportamiento del ñame (Dioscorea spp.)

Eighteen yam (Dioscorea spp.) cultivars from five species were evaluated for yield and severity of mosaic, anthracnose, and black leafspot (Curvularia spp.). Plantings were established at Mayagüez and Isabela, Puerto Rico, in the 1985-86 and 1986-87 growing seasons. Severe mosaic was found on D. trifida (Mina), which was the lowest producing cultivar both seasons. Five cultivars of D. esculenta (Kombi, Seti, Doli, Muni, and Beti) showed moderately severe mosaic symptoms in 1985-86, and black leafspot symptoms in 1986-87. Among these cultivars, Doli produced the highest tuber yields, 21,000 kg/ha (9.4 tons/acre). Among D. alata cultivars, differences in anthracnose were related to genotype, location, and season. Leon Globe and Forastero were the most susceptible and lowest yielding cultivars. Gunung produced the highest yield, a maximum of about 40,000 kg/ha (17.9 tons/acre). It was least affected by anthracnose, with less than 15% defoliation in November. Tuber yields in D. alata cultivars were highly associated with anthracnose severity ratings (r = —0.81 * *) . Both seasons more anthracnose was found in Isabela than in Mayagüez. Anthracnose was more severe in 1986-87 than 1985-86.Se evaluaron 18 cultivares de cinco especies de ñame (Dioscorea spp.) por su rendimiento y resistencia a mosaico, candelilla y la mancha negra en el campo durante 2 años consecutivos en Mayagüez e Isabela, Puerto Rico. La cultivar Mina de la especie D. trifida mostró síntomas severos de mosaico por lo cual arrojó una baja producción. Se evaluaron cinco variedades de ñame de papa, D. esculenta; todos mostraron síntomas de mosaico y ataques por la mancha negra de la hoja causada por Curvularia spp. La cultivar Doli sobresalió por su alta producción. En D. alata hubo gran variación en la severidad de la candelilla (antracnosis) causada por Colletotrichum gloeosporioides Penz. En los dos años hubo brotes de la candelilla más severos en Isabela que en Mayagüez. Leon Globe y Forastero fueron las cultivares más susceptibles a la candelilla. Gemelos fue severamente atacado por candelilla en Isabela en 1985-86 y moderadamente en 1986-87. Esta misma variedad resistió la candelilla en Mayagüez en 1986-87. Estas variaciones en reacción sugieren la existencia de distintas razas patológicas de Colletotrichum gloeosporioides en ñames en Puerto Rico o un gran efecto del lugar en la reacción de atracnosis