Soil and Water Protection Project (SOWAP) - so what?

Abstract

The SOil and WAter protection project (SOWAP) was created to take a holistic approach to comparing 'Conservation Agriculture' (CA) crop establishment methods, with more traditional mouldboard plough based systems. The Project operated in the UK, Belgium and Hungary. SOWAP followed the three main principles of CA; reduced/minimum tillage, permanent soil cover and appropriate crop rotations. The project assessed the economic, ecological, and environmental and yield outcomes, both methods were compared side-by-side. This paper gives an overview of the results gained and the conclusions made by the SOWAP team.
In general, soils vulnerable to erosion benefitted from reduced tillage and soil losses from the farmer's field were minimised. The effect being more pronounced in spring planted crops. With regard to water run-off and loss of nutrients from the field, results were more ambiguous, although nitrogen stood out as having run-off less from the reduced tillage fields. Many factors seem to play a part in generating benefits in this regard, not least the intensity of the agriculture and the length of time CA had been used.
The terrestrial and avian ecological benefits of reduced tillage came through quite strongly, although again cropping and other factors did seem to play a significant part. Certainly, in most soils, earthworm populations grew and soil microbial populations were enhanced, particularly fungi. In general, birds preferred to have their winter feed not buried by ploughing, but certainly CA on its own cannot save some of the UK's declining bird life populations, it will merely help.
Sadly, the results from the aquatic ecological work were not very edifying. It was difficult to make any firm conclusions. We know the team working in this area worked very hard, but the sheer variability of the data makes it difficult to come to any reasonable conclusion. This work needs to be redone, taking into account the complex nature of the task in hand.
Last but not least, did it make economic sense? This is the most vital question of all. Certainly input costs were reduced, and the more tillage was reduced, so then labour and fuel costs followed suit. However, it has to be said that taken in the round crop yields were reduced. This was not always the case, and certainly the margin for profitability was not severely impacted, as reduced establishment costs off-set any reductions in the yield. But if it ever comes to a world food shortage, the rest of any benefits may well be forgotten.
It is therefore the conclusion of the authors of this paper that CA does have a place in modern agriculture, especially to ensure the sustainability of agriculture land in areas at high risk of soil erosion. However, like many other approaches it cannot be taken as the panacea for all ills.