Organic farming and resource efficiency

The Chapter discusses the efficiency of nutrient and energy use in organic farming, regarding the pressing need to make efficient use of natural resources. Nutrient recycling, the use of adapted plant varieties and energy-saving through the ban of synthetic nitrogen fertilizer are organic farming practices that enhance resource efficiency

Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

Soil-borne amino acids may constitute a source of nitrogen (N) for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO<sub>3</sub><sup>−</sup>) and ammonium (NH<sub>4</sub><sup>+</sup>) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake, thereby resulting in similar total N uptake rates. Amino acids were enriched with double-labelled <sup>15</sup>N and <sup>13</sup>C, while NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup> acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup> did not differ from each other and were generally about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50% of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO<sub>3</sub><sup>−</sup> did not affect glycine uptake, while the presence of glycine down-regulated NO<sub>3</sub><sup>−</sup> uptake. The ratio between <sup>13</sup>C and <sup>15</sup>N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic N

Organic farm conventionalisation and farmer practices in China, Brazil and Egypt.

Certified organic agriculture stipulates a range of principles and standards, which govern farmer practices. The recent global expansion of organic agriculture has raised new challenges for organic agriculture, particularly whether management practices in organic farms are subject to the forces of conventionalisation. We studied changes in agroecological practices in certified organic farms in China, Brazil and Egypt. The study takes departure in the conventionalisation hypothesis and the analysis is framed using organic and agroecological principles. The study focuses on agroecological design principles, inherent to organic agriculture, of diversity in crop production, pest, disease and weed management, and soil fertility management. The research design was as a multiple case study of five cases in China, Brazil and Egypt. We show that the adoption of organic agriculture has induced fundamental changes in organic farmer management practices, although agroecological practices of organic farmers do not fulfil organic principles. The forces of conventionalisation exert a strong influence on changes in organic farmer practices. Organic ‘niche’ market crops with a high-value influence organic farmers’ management decisions, particularly regarding the prioritisation of diversity in the cropping systems for agroecological purposes. The farming systems have therefore not undergone major changes of their cropping patterns. Furthermore, there was a general heavy reliance upon input substitution for pest and soil fertility management. This study thus presents new data and a novel analysis of the implications at the farm scale of the global expansion of organic agriculture, and the influence of conventionalisation on farmers practices

Maize seed orientation in the substrate and its influences on germination, seedling structure, and transmission of Fusarium moniliforme

A research paper on maize seed orientation.The percentage of seedlings emerging during the first 4 days after sowing and the mesocotyl length after 7 days in sand at 25°C was strongly influenced by the orientation of the seed in the seedbed. Maize seeds emerged faster when oriented vertically with the pedicel end facing down (VD) or horizontally with the embryal side facing up (HU). The mesocotyl portion of the seedling was shorter (t 1mm) when sown at HU and VD, providing a fast and easy emergence to the seedling. It was much longer (20mm) when the seed was oriented horizontally with the embryal side facing down (HD) and vertically with the pedicel end facing up (VU). We concluded that the length of the mesocotyl portion of the seedling varies with the orientation of the seed in the substrate at the same depth. The seeds sown in the orientation HU and VU disclosed a higher germination of 95 percent and 88 percent respectively, compared to the seeds sown in the orientation HD and VD which had 68 percent and 53 percent germination respectively. Seed to seedling transmission of Fusarium moniliforme was recorded at a ratio of 1:1 in the untreated seeds, and infection of the fungus was found in the third leaf lamina and other sections of 10 day old seedlings. This demonstrates for the first time the systemic development of F. moniliforme above the crown portion of 10 day old seedlings. Treatment with Thiram contact fungicide improves the germination of highly infected seeds and also reduces the seed to seedling transmission of F. moniliforme. The efficiency of this seed treatment depended on the orientation of the seeds in the seedbed

Barriers to Agro-Ecological Intensification of Smallholder Upland Farming Systems in Lao PDR

Intercropping of legumes can be a strategy to improve soil fertility and enhance overall productivity while reducing dependency on external inputs in intensified cropping systems. Integration of legumes in maize-based cropping systems is promoted as an agro-ecological intensification option for input-constrained smallholders in uplands of Southeast Asia, but adoption rates in the region remain low. The overall aim of this study was to assess the suitability and trade-offs of integrating ricebean in maize-based smallholder cropping systems in upland areas of Northern Laos. We conducted a researcher-managed field trial to investigate the agronomic performance of ricebean/maize intercropping, and farmer-managed trials combined with surveys (N = 97), and focus group discussions in 10 villages to understand factors influencing farmers’ decision making concerning ricebean adoption. Drought, rat infestation and crop damage by grazing livestock were identified as important constraints to the production of ricebeans. Factors facilitating adoption included improvement of soil fertility, the potentially high selling price of ricebeans and the presence of extension agents, while barriers included labour shortage, concerns about competition with maize and lack of a market outlet for the ricebean produce. We conclude that the investigated maize/ricebean intercropping system is poorly suited to the current conditions in the study area, and call for farm-based studies focusing on developing locally adapted legume intercropping systems able to perform under variable rainfall conditions. Initiatives addressing challenges related to free grazing livestock and efforts to link legume producers in remote areas to emerging markets are also needed