A recent holiday trip took my family to Spain for 2 weeks. Travel throughout the central and eastern parts of the country took us through a lot of land devoted olive, grape, and citrus production.
But, it was the extensive areas devoted to cereal grain production, mostly winter wheat, that had my head on a swivel! And I had to remember that these were areas cultivated by numerous civilizations for spans measured in centuries, dating back to before there was a Christmas!
What really caught my attention was that nearly every cultivated field we drove past was clearly being tilled, usually moldboard plowed, prior to planting (see photos 1 and 2.)
Of the approximately 700 to 800 miles driven through predominately wheat-growing regions, I estimate that only a short 30-mile segment in one small area took us past fields that had been no-tilled (wheat no-tilled into wheat stubble).
But, it wasn’t the extent of the tillage that was grabbing my attention; the fact that the tillage of large areas was conducted following the longest dimension of the field, which often was up and down the slope…simply amazed me (see photo 3.)
True, much of that area experiences an arid climate and recent 20-year precipitation statistics list rainfall at approximately 17-22 inches per year. But, most of that total (14-18 inches), falls between September and May, before the soil is well protected by a heavy biomass.
It didn’t take long to find evidence of soil erosion (see photo 4). It was surprising to me that we didn’t see more instances of this, given the length and the steepness of the slopes being cultivated. Wheat is clearly the principle crop being grown, with little evidence of any other crops in rotation in many regions.
I kept wondering: why is so much tillage being practiced? The need to reduce disease pressure? Tradition dictates tillage ahead of planting? Low interest in trying something new? Little recognition of the potential for no-till to reduce erosion and to build soil structure and increase productive capacity, especially where precipitation is likely a yield-limiting input?
I can’t say for sure, but I suspect the answer includes some of all the above.