Under conditions of limited fixed-nitrogen, some filamentous cyanobacteria develop a regular pattern of heterocyst cells that fix nitrogen for the remaining vegetative cells. We examine three different heterocyst placement strategies by quantitatively modelling filament growth while varying both external fixed-nitrogen and leakage from the filament. We find that there is an optimum heterocyst f...

Most studies of input subsidy programmes confine their analyses to measuring programme effects over a one-year period. This article estimates the potential longer-run or enduring effects of fertiliser subsidy programmes on smallholder farm households' demand for commercial fertiliser and maize production over time. We use four waves of panel data on 462 farm households in Malawi for whom fertil...

Nitrogen (N) is a nutrient element necessary for plant growth and development. However, excessive inputs of N will lead to inefficient use and large N losses to the environment, which can adversely affect air and water quality, biodiversity and human health. To examine the effects of controlled-release fertilisers (CRF) on yield, we measured ammonia volatilisation, N use efficiency (NUE) and ph...

A study was conducted at Universiti Putra Malaysia, Malaysia, glasshouse to determine the inoculation effect of Sb42 (locally isolated diazotroph) with different doses of nitrogen fertiliser (0, 30 and 60kg N ha) on hydrolytic enzyme production and the growth of rice variety MR219. Using 16S rRNA partial gene sequencing, Sb42 was identified as Bacillus sp. Plants were harvested at 45 days after...

Introduction According to the National Greenhouse Gas Inventory (NGGI 2007) the agricultural sector contributes around 16% of national greenhouse gas emissions (Figure 1). The main greenhouse gases emitted from agriculture include methane lost during rumen digestion (enteric) and nitrous oxide lost from nitrogen fertilisers, animal excreta and soils (Figure 1). Agriculture accounts for 60% and ...

Treated municipal sewage sludge ("biosolids") and dairy cattle slurry (DCS) may be applied to agricultural land as an organic fertiliser. This study investigates losses of nutrients in runoff water (nitrogen (N) and phosphorus (P)), metals (copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr)), and microbial indicators of pollution (total and faecal coliforms) arising fro...

Nitrous oxide (N2O) is a potent greenhouse gas and the dominant anthropogenic stratospheric ozone-depleting emission. The tropospheric concentration of N2O continues to increase, with animal production systems constituting the largest anthropogenic source. Stable isotopes of nitrogen (N) provide tools for constraining emission sources and, following the temporal dynamics of N2O, providing addit...