Volatility Forecasting and Time‐varying Variance Risk Premiums in Grains Commodity Markets

In this paper we examine empirically the predictive power of model‐free option‐implied variance and skewness in wheat, maize and soybeans derivative markets. We find that option‐implied risk‐neutral variance outperforms historical variance as a predictor of future realised variance for these three commodities. In addition, we find that risk‐neutral option‐implied skewness significantly improves variance forecasting when added in the information variable set. Variance risk premia add significant predictive power when included as an additional factor for predicting future commodity returns.     

Optimising seed portfolios to cope ex ante with risks from bad weather: evidence from a recent maize farmer survey in China

Using 4‐year panel data collected from surveying 640 farmers from leading maize producing provinces in China, this study analyses how maize farmers cope with anticipated risks from bad weather by strategically adjusting variety portfolios, with particular interest in farmers' strategies in choosing and combining new and old varieties. While diversification was commonly demonstrated to be an effective means to reduce risk in most previous studies, our empirical results indicate that, in facing anticipated risks from bad weather, Chinese maize farmers tend to use fewer new varieties and allocate more land to old varieties. The lack of knowledge about weather tolerance of new varieties might be the major reason for this practice. As new varieties often have higher yield potential relative to old varieties due to technological progress, this finding suggests that Chinese maize farmers might be trading yield potential against risk reduction from bad weather. Furthermore, this study shows that maize farmers' variety adoption is significantly related to farmers' land conditions as well as their access to credit markets and technique extensions, suggesting that a well‐designed policy intervention could offset or partially offset the anticipation of adverse weather impacts on farmers' variety choices and therefore on maize production.     

Off‐farm Employment and Input Intensification among Smallholder Maize Farmers in Kenya

We derive input demand functions for fertiliser and hybrid seed, testing for the combined and separate effects of income from non‐farm sources and agricultural wage labour among smallholder maize farmers in Kenya. More income from off‐farm sources, and specifically non‐farm sources, competes with maize intensification, particularly in more productive areas where use rates are higher. In less productive areas, where households rely more on off‐farm income and input use in maize is extremely low, agricultural wage labour reduces the likelihood that fertiliser is applied, but when used, has a positive effect on quantities purchased of both seed and fertiliser.     

Agrarian Winners of Neoliberal Reform: The ‘Maize Boom’ of Sinaloa,Mexico

While the detrimental impact of neoliberal policy on Mexico's maize smallholders is well researched, little attention has been paid to the rise of maize in the northern state of Sinaloa. Sinaloa's entry into maize has restructured the geography of national supply, and generated a new national confidence in white maize self‐sufficiency. Using semi‐structured interviews and secondary data, we document the primary social and political drivers of Sinaloa's maize boom. Local actors trumpet Sinaloa's response as a success story of entrepreneurship and technological innovation, while simultaneously appropriating the language of food sovereignty to justify preferential entitlements in public investment. Our analysis confirms interpretations of neoliberalism as a political project, illustrating how existing natural, social and political capital held by specific interest groups can be leveraged and reinforced through private–public partnerships to mould national policy and investment, and the potential vulnerabilities that may emerge from this process.     

Reconstructing the Maize Market in Rural Mexico

The transition in Mexico from a maize market once characterized by heavy state intervention along the entire maize–tortilla chain to the ‘free market’ of today has been a long and complex process. Over two decades, the production of maize has seen a radical transition both in the geographical location of maize agriculture and the type of farmers growing maize. In this paper, I argue that the restructuring of the domestic maize supply is due to policy decisions to support private agents in the maize market; hence the state did not withdraw its involvement but, rather, has had a key role in the construction of the ‘free’ maize market, with the result that domestic supply for the market is concentrated in the hands of relatively few agents and in relatively few regions. I discuss the background to these policies and analyse the programmes implemented by the state agency ASERCA (Apoyos y Servicios a la Comercialización Agropecuaria) that support the commercialization of maize.     

Information Barriers to Adoption of Agricultural Technologies: Willingness to Pay for Certified Seed of an Open Pollinated Maize Variety in Northern Uganda

We examine smallholder farmers’ willingness to pay for agricultural technology and whether information is a constraint to adoption of certified maize seed in Northern Uganda. The uptake of improved maize varieties by smallholder farmers in Uganda remains persistently low, despite the higher yield potential compared to traditional varieties. A recently growing body of literature identifies information constraints as a potential barrier to adoption of agricultural technologies. We used incentive compatible Becker‐DeGroot‐Marschak auctions to elicit willingness to pay for quality assured improved maize seed by 1,009 smallholder farmers, and conducted a randomised evaluation to test the effect of an information intervention on farmers’ knowledge of seed certification. Our results show that the randomised information treatment enhanced farmers’ knowledge of certified seed. However, using the information treatment as an instrumental variable for knowledge, we find no evidence of a causal effect of knowledge on willingness to pay, suggesting that even though farmers are information constrained, this constraint does not affect adoption of certified seed directly. Nevertheless, only 14% of sampled farmers were willing to pay the market price, which corresponds closely with actual observed demand for certified seed in the previous season. This suggests that there are other barriers to adoption than information and awareness.     

Multi-Site Bundling of Drought Tolerant Maize Varieties and Index Insurance

Drought Tolerant Maize Varieties (DTMV) and Rainfall Index Insurance (RII) are potential complements, though with limited empirical basis. We employ a multivariate spatial framework to investigate the potential for bundling DTMV with a simulated multi-site and multi-environment RII, designed to insure against mild, moderate and severe drought risk. We use yield data from on-farm trials conducted by the International Maize and Wheat Improvement Center (CIMMYT) and partners over 49 locations in Eastern and Southern Africa spanning 8 countries and 5 mega-environments (dry lowland, dry mid altitude, wet lower mid altitude, low wetland and wet upper mid altitude) in which 19 different improved maize varieties including DTMV were tested at each location. Spatially correlated daily rainfall data are generated from a first-order two-state Markov chain process and used to calibrate the index and predict yields with a hierarchical Bayes multivariate spatial model. Results show high variation in the performance and benefits of different bundles which depend on the maize variety, the risk layer insured, and the type of environment, with high chances of selecting a sub-optimal and unattractive contract. We find that complementing RII with a specific DTMV produces contracts with lower premiums and higher guaranteed returns especially in dry lowland increasing the chances of scaling up RII within this environment.     

重金属镉污染对玉米种子萌发及幼苗生长的影响

研究不同浓度镉(Cd2 )胁迫对玉米萌发及幼苗生长影响,结果表明,当Cd2 浓度为5￣15mg/L时,Cd2 可以促进玉米种子的萌发,提高玉米的发芽势和发芽率,促进玉米芽与幼根的生长;当Cd2 的浓度高于50mg/L时,明显抑制种子萌发和幼苗生长。     

Unpacking a crop diversity hotspot: farmer practice and preferences in Northern Malawi

Crop diversity is a key principle of sustainable food production systems. Yet, inter and intra specific diversification is declining in many regions of the world. In Northern Malawi, a participatory action research project (Soils Food and Healthy Communities) has conducted agroecological co-learning with farmers for over a decade, providing an opportunity to explore farmer management, crop choice and variety selection practices. Farmers who participate receive seed for 0.10 ha of on-farm testing for one growing season and then decide whether to continue to grow the crop. Cropping system diversity, management practices and traits associated with crops grown and lost were assessed through interviews with 198 farm households (757 fields). We found an average of 1.3 species per field and 4.0 crops per farm. This is almost twice the level of diversity in other reports from Malawi smallholder farms. Farmers cited a wide range of preferred groundnut variety traits, as well as concerns (namely, high labour requirements). Both modern and local maize varieties are being grown and those retained were often associated with early maturity or preferred grain quality traits such as storability. Overall, farmers at this Northern Malawi agroecology education site are growing diverse crop mixtures that include traditional as well as modern varieties of maize and groundnut.