Tejendra Chapagain

Assessment of System of Rice Intensification (SRI) and Conventional Practices under Organic and Inorganic Management in Japan

Abstract The system of rice intensification (SRI) is a production system that involves the adoption of certain changes in management practices for rice cultivation that create a better growing environment for the crop. This system was compared with conventional practices and assessed under organic and inorganic management. SRI practices showed significant response in root number, number of effective tillers per hill, days to flowering and harvest index. In addition, SRI was found effective in minimizing pest and disease incidence, shortening the crop cycle, and improving plant stand. Grain yield was not different from conventional method. Except for harvest index and plant lodging percentage, there were no significant effects from management treatments. Synergistic responses were noted when SRI practices were combined with organic management for plant height, number of effective tillers per hill, days to flowering and to maturity. The improved panicle characteristics, lower plant lodging percentage and higher harvest index that ultimately led to comparable grain yields. Net returns increased approximately 1.5 times for SRI-organic management regardless of the added labor requirements for weed control. However, comparatively higher grain yield from conventional-inorganic methods underscore the need for further investigations in defining what constitutes an optimum set of practices for an SRI-organic system specifically addressing grain yield and weed management.

Yield and Production Gaps in Rainfed Wheat, Barley, and Canola in Alberta.

Improving crop yields are essential to meet the increasing pressure of global food demands. The loss of high quality land, the slowing in annual yield increases of major cereals, increasing fertilizer use, and the effect of this on the environment all indicate that we need to develop new strategies to increase grain yields with less impact on the environment. One strategy that could help address this concern is by narrowing the yield gaps of major crops using improved genetics and management. The objective of this study was to determine wheat (Triticum spp. L.), barley (Hordeum vulgare L.), and canola (Brassica napus L.) yields and production gaps in Alberta. We used 10 years of data (2005–2014) to understand yield variability and input efficiency at a farmers’ specified level of management, and the yield potential under optimal management to suggest appropriate pathways for closing yield gaps. Significant management gaps were observed between attainable and actual yields of rainfed wheat (24%), barley (25%), and canola (30%). In addition, genetic gaps (i.e., gaps due to genetic selection) in wheat, barley, and canola were 18, 12, and 5%, respectively. Genetic selection with optimal crop management could increase yields of wheat, barley, and canola significantly, with estimated yield gains of 3.42, 1.92, and 1.65 million tons, respectively, each year under rainfed conditions in Alberta. This paper identifies yield gaps and offers suggestions to improve efficiency in crop production.

Erratum to: Belowground nitrogen transfer from legumes to non-legumes under managed herbaceous cropping systems. A review

Nitrogen is the most limiting nutrient in most agro-ecosystems and thus critical for sustaining high yields. Conventional agricultural practices use synthetic fertilizers to ensure an adequate supply of nitrogen in soils, but fertilizers come at a significant monetary and environmental cost. A strategy to improve nitrogen supply in cropping systems is the inclusion of nitrogen-fixing legumes, which can provide nitrogen benefits to companion crops through belowground nitrogen transfer. However, a better understanding of the underlying mechanisms and factors that govern nitrogen transfer is important in order to determine potential areas for improving this association. Here, we review the mechanisms of belowground nitrogen transfer in managed herbaceous cropping systems, focusing on forage systems. We classify three major routes of nitrogen transfer from legumes to non-legumes: (1) decomposition of legume root tissues and uptake of mineralized nitrogen by neighboring plants, (2) exudation of soluble nitrogen compounds by legumes and uptake by non-legumes, and (3) transfer of nitrogen mediated by plant-associated mycorrhizae. Literature data shows that rates of nitrogen transfer range from 0 to 73 % from forage legumes to companion grasses in mixed stands, depending on the legume species and cultivar. We list the factors that affect nitrogen transfer including abiotic factors, e.g., water stress, temperature, light, soil available nitrogen, and application of nitrogen fertilizer, and biotic factors, e.g., root contact, plant density, growth stage, production year, defoliation, and root herbivores. While the rates of nitrogen transfer are often constrained by abiotic conditions, such as temperature and water availability, that are beyond the control of growers, agronomic practices, e.g., planting density and choice of species and cultivar, may help to increase nitrogen transfer. Ultimately, the selection of plant pairs with compatible traits offers the best path forward to improving nitrogen transfer in intercrops.

Root architecture variation in wheat and barley cultivars.

Aims: We analyzed root architecture varia tion among heirloom and commercial cultivars of wheat and barley to improve our understanding of the quantitative variation present within small grain root architectures. We also compared lab-based root architecture measures with cultivarshoot:rootratiosand field data. Study Design: This study had a c

Agronomic Challenges and Opportunities for Smallholder Terrace Agriculture in Developing Countries

Improving land productivity is essential to meet increasing food and forage demands in hillside and mountain communities. Tens of millions of smallholder terrace farmers in Asia, Africa, and Latin America who earn

Barley–pea intercropping: Effects on land productivity, carbon and nitrogen transformations

1–2 per day do not have access to peer-reviewed knowledge of best agronomic practices, though they have considerable traditional ecological knowledge. Terrace farmers also lack access to affordable farm tools and inputs required to increase crop yields. The objectives of this review are to highlight the agronomic challenges of terrace farming, and offer innovative, low-cost solutions to intensify terrace agriculture while improving local livelihoods. The article focuses on smallholder farmers in developing nations, with particular reference to Nepal. The challenges of terrace agriculture in these regions include lack of quality land area for agriculture, erosion and loss of soil fertility, low yield, poor access to agricultural inputs and services, lack of mechanization, labor shortages, poverty, and illiteracy. Agronomic strategies that could help address these concerns include intensification of terraces using agro-ecological approaches along with introduction of light-weight, low-cost, and purchasable tools and affordable inputs that enhance productivity and reduce female drudgery. To package, deliver, and share these technologies with remote hillside communities, effective scaling up models are required. One opportunity to enable distribution of these products could be to “piggy-back” onto pre-existing snackfood/cigarette/alcohol distribution networks that are prevalent even in the most remote mountainous regions of the world. Such strategies, practices, and tools could be supported by formalized government policies dedicated to the well-being of terrace farmers and ecosystems, to maintain resiliency at a time of alarming climate change. We hope this review will inform governments, non-governmental organizations, and the private sector to draw attention to this neglected and vulnerable agro-ecosystem in developing countries.