Harry Nesbitt

Degradation of the herbicide 2,4-D in river water - II. The role of suspended sediment, nutrients and water temperature.

Abstract The rate of 2,4-D degradation in the Avon River was related to the nutrient concentration, sediment load and dissolved organic carbon content of the water. Addition of sediment and inorganic nutrients increased the rate of 2,4-D degradation, however addition of actively involved organisms did not. This indicates that the rate of 2,4-D breakdown was dependent upon the nutrient status of the river and not the availability of organisms capable of degrading the herbicide. During the winter, when the river flow rate was at its peak the water temperature was well below optimum for bacterial activity. It is therefore likely that an appreciable amount of 2,4-D washed into the river during winter will eventually be transported into the river estuary.

Household food insecurity in Timor-Leste

Timor-Leste is among the world’s youngest and poorest countries. It suffers from seasonal food insecurity and has the third-highest stunting rate globally. Previously inadequately documented, this paper summarises recent advances in understanding household food security in Timor-Leste and the multifaceted approaches being used to overcome it. Information comes from the extensive annual surveys of the Seeds of Life (SoL) program in Timor-Leste. The hungry season prior to maize and rice harvests is the key issue in household food security in Timor-Leste. Farm households cope with the problem through crop diversification with tubers playing a lead role as grain stocks dwindle. Foraging for wild food resources, selling animals and other assets, and social networks are other coping strategies. To address seasonal food insecurity, the government has focused on rice importation and the improvement of agricultural productivity within a multi-dimensional program. Information on storage by households of the key staple, maize, indicates an improving trend in food security at the household level from 2006/2007 to 2010/2011 through a significant reduction in the percentage of ‘at risk’ households—those who grow insufficient maize for storage during the year. The current emphasis on the widespread dissemination of the new high-yielding SoL cultivars has the potential to augment these improving trends. Nevertheless this picture remains vulnerable to weather shocks—such as drought—which are anticipated to increase with climate change and it is important to build further resilience into the agricultural systems of Timor-Leste.

Degradation of the herbicide 2,4-D in river water—I. Description of study area and survey of rate determining factors

Abstract The biodegradation of 2,4-D incubated in river water at 25°C was dependent upon the bacterial activity rather than the initial quantity or species of organisms present. Microbial activity was related primarily to the nutrient content and distribution of sediment in the water. The two major elements, phosphorus and nitrogen were in such low concentration that their effect on the biodegradation of 2,4-D was difficult to detect. Further investigations on nutrient levels, and temperature effects are required.