ANALYSIS - For several years it has been a constant debate. Till or no-till? New research suggests no-till farming may be the way forward - for now, writes Gemma Hyland.
Tilling prepares the soil for planting by removing residue from the previous crop, but for some time there has been speculation over the benefits of no-till farming - a key conservation agriculture strategy that avoids conventional plowing.
New meta-analysis by an international team suggests that no-till farming may not bring a hoped-for boost in crop yields in much of the world.
As the core principle of conservation agriculture, no-till has been promoted worldwide in an effort to sustainably meet global food demand.
But after examining results from 610 peer-reviewed studies, the researchers found that no-till often leads to yield declines compared to conventional tillage systems, except it still shows promise for yield gains in dryland areas.
Conservation agriculture is currently practiced on 125 million hectares of land globally, an area nearly as big as the total US cropland.
Three key principles guide the concept: minimizing soil disturbance (also called no-till farming), protecting the soil with cover crops or leftover crop residue, and rotating the crops.
The goals of conservation agriculture are to improve long-term productivity, profits, and food security, particularly under the threat of climate change. Because conservation agriculture avoids tillage, it is less time-consuming and can be more cost-effective than conventional farming methods.
In recent years, however, there has been some disagreement about the impact of no-till farming practices on yield.
After assessing more than 5,000 side-by-side observations, the researchers concluded that on average no-till negatively impacts yields at the global scale, yet several opportunities exist for more closely matching or even exceeding conventional tillage yields.
For example, yield reductions were minimized when the principles of crop rotation and residue retention were also practiced, highlighting the importance of implementing all three conservation agriculture principles as part of an integrated management system rather than no-till alone.
Moreover, when adopted in dry climates in combination with the other two principles of conservation agriculture, no-till farming performed significantly better than conventional tillage, likely due to the higher retention of soil moisture.
Dryland ecosystems are home to 38 per cent of the world’s population, and millions of acres of land in arid regions of sub-Saharan Africa and South Asia have been identified as suitable for sustainable intensification.
Yet the authors also caution that practicing no-till in dryland areas without the implementation of the other two principles of conservation agriculture decreases yields.
In regions with moist climates and sufficient precipitation, no-till farming actually resulted in yields that were on average 6 to 9 per cent lower than with conventional tillage methods.
The findings were published in the journal Nature.
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