Cassava rapid stem multiplication tunnel: Construction manual

This manual will teach you how to build a rapid stem multiplication tunnel based on CIAT’s experiences in Colombia and Lao PDR . These tunnels have been developed by CIAT and tested in South America and Asia, proving to be practical solutions for rapid production of clean planting materials

Cassava rapid stem multiplication tunnel: Operations manual

This manual explains how to manage a cassava rapid stem multiplication tunnel system. A previous manual in this series described the construction of tunnels using common, locally available materials. In this manual, based on experiences from tunnel managers in Cambodia, Colombia, Lao PDR, and Vietnam, we describe the major stages and operations for rapid multiplication of cassava planting stems using the tunnel system

Impacts of the continuous maize cultivation on soil properties in Sainyabuli province, Laos

Abstract In tropical mountainous areas, soil degradation and yield decrease have been anticipated due to conversion from shifting to continuous cultivation and the introduction of cash crops. In our previous report, we quantified the decrease in maize yield under continuous cultivation in farmers’ fields in Laos. In this report, we focused on soil nutritional conditions under continuous cultivation in the farmers’ fields. For the purpose, twelve soil properties were investigated over two years from three sample sites in each of the 40 farmers’ fields with the duration of continuous cultivation varying from 1 to 30 years. Total carbon (TC), total nitrogen (TN), available phosphorus, exchangeable potassium, and exchangeable calcium in the soil decreased with increasing duration of continuous cultivation in the sloped fields. These soil nutrients decreased to around half of the initial content in these 30 years. However, the decreasing rates of TC and TN were negligible in the flat fields. Other soil properties such as clay and exchangeable magnesium were not related to the duration of continuous cultivation in both sloped and flat fields. The reduction in maize yield was mainly explained by TC, but the determination coefficient was only 0.24. Although further analysis is required to quantify the effect of soil nutrients on maize production, the development of integrated soil management would be necessary in the sloped fields for sustainable crop production in the study site

Potassium Fertilisation Is Required to Sustain Cassava Yield and Soil Fertility

Cassava is often grown in low-fertility soils and has a reputation for having modest nutrient requirements. The storage roots that are harvested, however, contain relatively large amounts of potassium (K). We carried out a field experiment in Laos to determine the growth response to K fertiliser and to examine the field’s K balance over the cropping season. Four different rates of K (0-40-80-120 kg K2O equivalents ha−1) were applied to cassava variety Rayong11. Harvests were done at 8 and 10 months after planting, when the crop was at early and full maturity respectively, to assess if any benefits for productivity or K balance could be achieved by early harvest. We found a positive effect of K fertiliser (up to 39% yield increase compared to no K fertiliser at early harvest, 21% at late harvest) and a positive effect of late harvest (on average a 35% increase compared to early harvest) on cassava root yield. Low-K crops benefited more from a late harvest. At 10 months, the harvested cassava contained 99–142 kg K ha−1, indicating that there was a net removal of K from the fields, even at high K fertilisation levels. This experiment was carried out in comparatively fertile soil with relatively high background K levels, yet, yield benefits of K fertilisation were observed and soil K reserves were depleted by the harvest. It can be concluded that K fertilisation of cassava is advisable for better yields and to avoid progressive depletion of the soil K capital