Vegetable soil health systems for overcoming limitations causing soil borne diseases
The vegetable soil health project aimed to find more sustainable methods for producing vegetables in Queensland and New South Wales. The project worked on long term field trials and commercial farms to determine how management could be improved to take advantage of greater soil biological activity and diversity, while economically producing vegetable crops. The focus in Queensland was on minimum tillage, organic mulch systems and how growers could switch from the intensive “plasticulture” systems, without suffering yield penalties. The work in New South Wales focused on nutrient management and the use of composted garden organics at a long term field trial at the Centre for Recycled Organic Agriculture in Camden. The Australian vegetable industry is under increasing pressure to cut costs, improve product quality and protect environmental resources. The improvement of soil health is seen as a step to resolve these problems, although changes often require new knowledge, capital investment and greater risks. Vegetable growers are not willing to change management practices if there are penalties to production or product quality. The aim of this project was to develop a greater understanding of management practices that have the potential to overcome soil constraints and enhance biological activity and diversity. There was a trend for increased soil organic matter in management systems that promote soil health. These systems produced equivalent yields to conventional systems, with greater produce quality. However changes in soil properties take time to occur and the full potential of such systems was not realised over the length of this project. Vegetable growers adopting new farming systems need to be aware of their particular soil constraints to vegetable production. When inputs are reduced there is a greater emphasis on soil processes to maintain productivity and quality. This requires modifications to machinery as well as management of nutrients and water during crop production. Vegetable production systems that increased organic matter in the soil appeared to be more durable to environmental stress allowing produce quality to be maintained. This project made some progress towards understanding the effect of various management practices in vegetable production systems and the benefits of studying practice change in long-term field trials. However there is still a need for a greater understanding of soil biological activity and how this is affected by vegetable management practices. The development of new farming systems that promote soil health need to undertake regional development to ensure they are relevant to local producers and systems need to be flexible whilst under development to respond to new information as it becomes available and deal with challenges as they arise. Important lessons were learnt during this project. When converting to minimum tillage systems growers should be aware that soil compaction may be a problem and consider zone tillage or specially designed equipment. More precise management of nutrients and water are required, particularly under organic mulch systems, which lose more soil moisture than plastic mulch. However, the benefits from the increased soil organic matter not only provide a more active and diverse soil biology but can improve the quality of vegetables.