No abstract

On-farm diversification is a promising strategy for farmers to adapt to climate change. However, few recommendations exist on how to diversify farm systems in ways that best fit the agroecological and socioeconomic challenges farmers face. Farmers' ability to adopt diversification strategies is often stymied by their aversion to risk, loss of local knowledge, and limited access to agronomic and market information, this is especially the case for smallholders. We outline seven steps on how practitioners and researchers in agricultural development can work with farmers in decision-making about on-farm diversification of cropping, pasture, and agroforestry systems while taking into account these constraints. These seven steps are relevant for all types of farmers but particularly for smallholders in tropical and subtropical regions. It is these farmers who are usually most vulnerable to climate change and who are, subsequently, often the target of climate-smart agriculture (CSA) interventions. Networks of agricultural innovation provide an enabling environment for on-farm diversification. These networks connect farmers and farmer organizations with local, national, or international private companies, public organizations, non-governmental organizations (NGOs), and research institutes. These actors can work with farmers to develop diversified production systems incorporating both high-value crops and traditional food production systems. These diversified farm systems with both food and cash crops act as a safety net in the event of price fluctuations or other disruptions to crop value chains. In this way, farmers can adapt their farm systems to climate change in ways that provide greater food security and improved income.

, J. R. 2009. The influence of crop rotation on the mineral nutrient content of organic vs. conventionally produced wheat grain: Preliminary results from a long-term field study. Can. J. Plant Sci. 89: 915Á919. The effects of farming system (organic vs. conventional) and crop rotation (annual grain vs. grainforage) on the mineral nutrient content of wheat (Triticum aestivum) grain was tested in a long-term field study in Manitoba. Crop rotation affected phosphorus (P), manganese (Mn) and copper (Cu) concentrations, while system affected nitrogen (N) and sulphur (S) concentrations. Interactive effects were observed for N, P, S, and zinc (Zn). This preliminary study demonstrates that differences in nutrient content between organic and conventional wheat depend on crop rotation and suggests that crop rotation should be considered in studies comparing the quality of organic and conventional produce.Key words: Crop rotation, organic crop production, mineral nutrient content, wheat Turmel, M.-S., Entz, M. H., Bamford, K. C. et Thiessen Martens, J. R. 2009. Incidence de l'assolement sur la concentration d'oligoe´le´ments chez le ble´cultive´de fac¸on biologique ou classique : premiers re´sultats d'une e´tude sur le terrain de longue haleine. Can. J. Plant Sci. 89: 915Á919. Les auteurs ont examine´l'incidence du syste`me agricole (culture biologique ou classique) et de l'assolement (culture annuelle ou assolement grain-fourrage) sur la teneur en oligoe´le´ments des grains du ble´(Triticum aestivum), dans le cadre d'une e´tude sur le terrain de longue haleine tenue au Manitoba. L'assolement modifie la concentration de phosphore (P), de mangane`se (Mn) et de cuivre (Cu), tandis que le syste`me agricole affecte celle d'azote (N) et de soufre (S). Les auteurs ont observe´des interactions entre le N, le P, le S et le zinc (Zn). Cette e´tude pre´liminaire indique que la variation de la concentration d'oligoe´le´ments observe´e chez le ble´cultive´de fac¸on biologique ou classique re´sulte de l'assolement et qu'on devrait tenir compte de ce facteur dans les e´tudes qui comparent la qualite´des produits agricoles biologiques et traditionnels.

The System of Rice Intensification (SRI) is a low-input rice (Oryza sativa L.) production system that differs from conventional systems in several ways: seedlings are transplanted earlier and are more widely spaced, organic fertilizer is often used in addition to mineral fertilizer, and soils are irrigated intermittently rather than flooded for long periods. The yield benefits of SRI compared to conventional systems can be substantial, and yet are regionally variable and have been the subject of considerable debate, due partly to a lack of mechanistic understanding. Here we show that soil properties may in part explain the variability in yield response to SRI. A meta-analysis of data from 72 field studies where SRI was compared with conventional systems indicates that yields increased significantly (P < 0.0001) when SRI was implemented on highly weathered infertile soils rich in iron and aluminum oxides (Acrisols and Ferralsols), but there was no difference in yield between SRI and conventional systems in more fertile favorable soils for rice production (Gleysols, Luvisols and Fluvisols). The yield difference between SRI and conventional rice production therefore appears to be related in part to soil properties linked to weathering. This should help resolve the debate about the value of SRI and allow research to be targeted toward understanding the biological and chemical processes in soils under SRI management.

Conservation agriculture (CA) has been widely successful in the Southern Cone region of South America. A leader in the development of CA practices and technology, Brazil has encouraged the spread of CA throughout the region through an effective and innovative network of farmers and their associations, private and public partnerships. The benefits of CA in Latin America include soil conservation, reduced production costs, and increased soil biodiversity, which enhances environmental equilibrium, improves crop water balance, and increases yields. In other regions of Latin America, however, such as Central America and the Andean region, CA adoption has proven more difficult. A review of case studies in Latin America suggests that CA adoption is limited by socioeconomic constraints, access to appropriate machinery, crop-residue trade-offs, lack of adaptation of the technology to farmer's agronomic constraints, and uncoordinated efforts of stakeholders. The development of effective CA innovation systems in countries such as Brazil and Mexico has been instrumental in overcoming factors limiting CA adoption and reflects the importance of collaboration between public and private sectors, including machinery manufacturers, as well as the need for positive incentives and lowinterest loans to make technology affordable for farmers. In addition, CA education, information dissemination through extension agents and farmers, and greater policy support and social capital, can help change attitudes and conventional farming practices.

Biofertilizers are considered as potential supplements or alternatives to fertilizers. The objective of the present study is to evaluate different biofertilizers in combination with synthetic fertilizers on the yields of maize and wheat in several states in Mexico. Fourteen biofertilizer treatments plus a treatment with 100% the locally recommended fertilizer rate (RFR), another with 50% RFR (the control treatment), and one without any fertilizer (for a total of 17 treatments) were tested on maize and wheat in five states across Mexico. Field experiments were established in five states and several years for a total of 14 experiments in Mexico. In general, except for the experiments conducted in moderately low soil P conditions, Chiapas and Sonora (maize), no response to biofertilizers was observed in the remaining locations, through the years in wheat and maize. We conclude that in high input production systems, the biofertilizer response is more an exception than a rule with only 21% of the experiments showing a significant difference in favor of biofertilizers and only 4 of 15 products tested produced a yield response in more nitrogen deficient environments. Some products containing AMF may be beneficial in maize production systems with phosphorus deficient environments.

On-farm trials were conducted to evaluate the potential of the System of Rice Intensification (SRI), a lowinput crop management system, to increase rice yields and reduce water consumption on subsistence farms in several regions of Panama and to determine how inherent soil fertility might affect SRI yields and the yield response to SRI management in the first season of SRI management. SRI practices increased yield by 47% on average and showed potential to increase yield by over 90%, while reducing water consumption by as much as 86%. SRI yields were correlated with available soil K and the difference between SRI and the conventional system yields was positively correlated with extractable Ca, Mg and Mn. The results of this study indicate that SRI is a promising rice production system for smallholder farmers in rural Panama farming under Panamanian soil conditions.

No abstract