To increase agricultural productivity, ZZ2 approaches soil health management holistically. This approach implies optimising and integrating the chemical, physical and biological properties of soil. According to Bombiti Nzanza of ZZ2’s agronomy department, this holistic approach to soil health was developed over the years and was affirmed by ZZ2’s visit to Cornell University in the USA in June last year.
In the past ZZ2 placed emphasis mainly on the biological components of soil such as fungal or bacterial ratio to determine whether it could be considered healthy or not. However, a presentation by Prof. George Abawi of the Cornell Soil Health Program Work Team two years ago set the ball rolling towards a more holistic and integrated approach towards soil health comprising the chemical, physical and biological components of soil.
The Soil Health Program at Cornell offers training on an annual basis and a number of ZZ2’s agronomists were invited to attend these workshops. According to Nzanza, the first step in the training was to identify soil constraints. These constraints can take many forms, including soil degradation, soil compaction, low cation exchange capacity (CEC) or soil-borne diseases.
Once the soil constraints have been identified, priorities are set to solve these problems. Soil management practices are then implemented. These could, for example, include the planting of cover crops, minimum tillage or the use of compost. A third element in soil health management is to compile a history of the soil so that it becomes clear what happened with the soil in question in the past. The final step is to select the most appropriate soil management practices to remedy the problem.
According to Nzanza there are currently four main strategies that could be followed to manage soil health. The first is to plant a cover crop – usually early grasses or legumes - to improve soil health. Marigolds can, for example, help to alleviate a problem with nematodes, whereas other plants can help the soil to retain nutrients. Secondly, organic amendments can be used such as compost or manure. The third strategy is to look at tillage and apply minimum tillage, if appropriate. The final strategy is to look at crop rotation. This could pose a problem at ZZ2, as the lands in question bear a mono-crop, namely tomatoes.
Nzanza stresses that it is not necessary to apply all four of these strategies at once. If one – such as crop rotation, for example – is not viable, the other strategies can be implemented.
One of the soil health management strategies that do not fall within the four mentioned above is microbial inoculants. This is widely used at ZZ2.
Nzanza is of the opinion that the most important new process brought back from the USA is the implementation of the Cornell Soil Health Tests. Previously the agronomists at ZZ2 would take soil samples which would be analysed for their chemical properties at ZZ2’s soil health laboratory. In certain cases the soil biology would also be analysed. The Cornell Soil Health Tests, however, do not look at these analyses in isolation, but rather propose that the chemical, physical and biological make-up of the soil should be analysed in an integrated way to get the best solution to solving soil health problems.
Finally it is important to remember that the aim of all of these strategies mentioned is to improve soil health which in turn would lead to improved crop productivity.
The cooperation between ZZ2 and Cornell is ongoing. At the moment the ZZ2 agronomists are collecting data to contribute to Cornell’s research. It is hoped that more scientific papers on soil health will see the light in the near future due to this partnership.