The long absence in writing about the farms has been on account of equipment breakdowns and a season of crop losses due to excessive rainfall in the district. In short, the kharif season of farming this year has been rife with difficulties and losses.
But this post is about tilling and crop residue management. The latest evidence indicates that there is no observable yield improvement by practicing no-till farming. On the contrary, there are chances of yield loss. As for crop residue, addition of residue to the land by tilling it into the soil (than clearing it out from the plot) shows improvement in crop yield ranging from 9-25% by the end of 8th cropping cycle. These are important findings.
I am excited by this kind of research because of its high relevance to current discourse on farming methods and the serious potential of input cost reduction as well as yield improvements. The paper – Evaluating the trade-offs and sustainability of minimum tillage and crop-residue addition for food production in the dryland tropics published in The Indian Journal of Agricultural Sciences is based on a long-term study.
In April, 2022 we bought a heavy duty RMB plough for land preparation which is done at the start of every round of cropping. This plough is meant for deep tilling. We found it a necessary part of land preparation and crop residue management processes on the farm. Even as it was being considered, I poured over agricultural research on the subject of tilling as a land preparation method and its impact on yield.
There has been extensive debate on tilling vs no-tilling approach to farming. For me, the argument for no-till has been hard to understand, especially because of lack of credible evidence from farms. At the same time, I had anecdotal evidence from our farms and across ten farming seasons on consistent yields and pest management improvements. We see a need for tilling as soil on our farm plots show high levels of compaction.
The authors conclude –
The effects of residue addition were inconsistent till the third year of experiment. However, yield benefits from residue addition became apparent fourth year onwards. After 7 years, residue addition showed significant yield benefits to the tune of 9–25% during 2016–17 (8th cropping cycle) and 18–31% during 2017–18 (9th cropping cycle) in both cropping systems. Residue addition also resulted in additional net income of
16,900/ha to22,980/ha compared to no-residue addition. Minimum tillage in general tended to result in yield loss over normal tillage since beginning. During 8th and 9th cropping cycles, there was net annual loss up to `5400/ha under minimum tillage. Alongside productivity and economic benefits, at the end of 8th year i.e. 2016–17, residue addition showed improved soil health and sequestered around 300 kg carbon/ha/year.
I have been suggesting that there are a few critical stages in a typical cropping cycle that a small holder (or any farmer!) will not mess around with. Tillage and sowing are two such stages. It will be a hard push for environmentalists and sustainability activists to push for zero tillage if there is even a slightest suspicion in a farmer’s mind that it will impact the crop yield. Even though deep tilling in our region can cost upto INR 2000/acre of land, the cost is still taken on board by the farmers in the interest of guaranteed yield.
I am glad that the scientists at ICRISAT and state agricultural universities are responding to these debates with high quality research. Crop residue addition to the soil is a fairly accepted practice. But there are competing uses for crop residue. Therefore, instead of being prescriptive on crop residue management, it may be a better option to emphasize on soil health and presenting a set of options to maintain soil health after every round of cropping.