Assessment of Waste for Use on Agricultural Land

The disposal of waste to agricultural land requires a systematic and transparent assessment procedure to ensure environmental and production sustainability. A hybrid model of risk assessment used in the general risk, environmental management and the mining industries was developed and tested using the waste from a yeast factory. The model is systematic and cybernetic and develops a succession of decisions that have the capacity to focus the environmental and agronomic considerations down to individual crops, land and management systems. The process directly links environmental risk assessment and development of management plans to agronomic development of the use waste products

Environmental Hazard of Excess Dunder on Agricultural Land

The use of high biochemical oxygen demand (BOD) organic waste on farming land offers two resource recovery opportunities, first nutrient for plant production and secondly organic matter for soil health. One such waste, dunder from yeast production was tested for its impact on irrigated lucerne hay production. A randomised complete block trial with five treatments (0, 8, 24, 48, 96 L dunder m-2)and three replications was used to test the impact of dunder on total dry matter production. The trial showed that the lower rates of 8 and 24 L m-2 of dunder was not significantly different to the control (0) while the high rates of 48 and 96 L m-2 significantly reduced total dry matter. This was significant as it identified limits to dunder application rate. However, more importantly, the trial showed that site characteristics and agronomic management had greater impact than the dunder alone on the plant production. In this trial a sodium hazard not related to the dunder significantly added to the reduction of dry matter. The results show that the assessment of dunder and other similar wastes for land application must include both the direct and indirect site related consequences of application to agricultural land

Cumulative Effect of the Application of N and P Fertilizers on Soil Total and Labile Concentrations After 12 Cereal Crops on a Black Vertosol

Soil organic carbon is commonly used as a key indicator of sustainability of farming systems due to effects on nutrient availability, structural stability and its central role in soil biotic processes. Trends in total carbon content (CT) and lability of carbon (CL) in soil have been measured in a long-term nitrogen (N) x phosphorus (P) fertiliser experiment in continuous cereal cropping to assess the effect of increasing crop nutrient supply on soil carbon accretion and partitioning. Increasing N supply in each crop by 80 kg/ha or more was effective in creating significantly different total and labile carbon content