Saturday, 15 July 2006

No-Till Requires Better Soil.

Frédéric Thomas, Farming Communication, Amillé, Marcillé-Robert, France

If it is true that no-till helps to recover better soil with more earth worms, organic matter and porosity, no-till also requires better soil to be implemented safely under Western European conditions. That is the statement we have made so far with many other farmers involved in conservation agriculture. This means that no-till must be preceded, in many cases, by a period where the main objective of the farmers will be, with the help of conservation tillage, cover-crops, liming, organic matter spreading as well as rotation adjustment, to improve soil structure, soil life and soil fertility in order to be able to succeed in direct drilling. We are farming in very low fertility soil made principally of a sand layer settled on a waterproof clay pan. On one hand, this kind of soil is very wet in winter with a lot of water logging problems so many of the farmers plow and leave furrow every 12 m to evacuate the excess water. On the other hand, this soil is also too dry at the end of spring and summer. Consequently yields are low (4 to 6 t of wheat /ha) and the organic matter level very poor (less than 1 %). We first thought we just had to suppress tillage to help to improve those soils but failures rapidly showed us we had to reconsider our soils and really implement a global soil improvement strategy to get away from compaction, bad yields, poor cover crops and even weeds problems. In this respect, we came back to some kinds of no inversion tillage in order to break compacted layers and to maintain enough porosity to keep good soil physical performances. We also start to bring and spread compost (10 t/ha/year) from a local city in order to gain rapidly a better level of organic matter, bring nutrients and especially many missing trace elements and feed the soil life. We finally, among many other minor changes, developed with the help of A. Calegari (IAPAR Brazil) a better cover crop approach with mix and now legumes sown earlier (just after harvesting). The objective here is to produce the maximum of biomass to hold the structure and feed the soil but also to dry it before the winter to reduce the hydromorphic period as well as to develop through nutrients cycling higher soil auto fertility. Today we currently achieve 6 to 7 t/DM/ha in 3 summer months and 10t/DM/ha seems to be feasible in the near future with new species and mixes as well as greater soil fertility. This global strategy took some time to show its first positive results but after 5 years we were able to return the better fields to no-till and progressively few others over the last 3 years. Surprisingly the yields have really improved and are better than in conventional tillage especially for summer crops. Better yields means also better soil structural effects of the crop and greater return of residues to support the improvement of the soils. We are even starting to see roots and earth worms colonizing the waterproof clay pan, making us think that we are on the way to turn what has been a restriction in our soils for many farming generations in an advantage through its water storing capacity in the future. This is, of course, only one example in a very limited soil area but it illustrates with a big magnitude, some of the problematic that are facing many farmers switching for Conservation Agriculture in France: the need to adopt a global soil strategy first in order to succeed in no-till.

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