Sunday, 3 March 2013

Did The Earth Move For You?

I have been doing quite a lot of driving recently and it's been interesting looking over the hedge to see exactly what has been going on.  This year I have seen far more poorer fields than good ones, no reflection on the farmers just as a consequence of the weather we have been having.  I spotted this field the other day and it reminded me of exactly how vulnerable we are to the weather and how much damage can be caused.  This group of fields is by no means a one-off this year but I thought it would highlight the precarious position our soils, under our management, find themselves in.  The fields would be classed as a clay loam, not much sand and may be a little silt, fairly heavy but not excessive.
The slope of the field wouldn't be great, nothing to really get alarmed with, I think it was even planted with winter wheat.  At the bottom of the field there was literally tonnes and tonnes of soil that had eroded down from the higher parts of the field. With that soil would have been any metaldehyde slug pellets or herbicides that would have been applied to the field.  What highlighted this field to me, driving passed, was the soil on the road and I was staggered that so much could have eroded from a fairly benign, short slope.  I think there have been a culmination of factors in conspiracy here.  Firstly the seed bed could have been too fine, causing the soil particles to run together capping the soil surface making subsequent rain events wash over the soil surface.  I suspect the farmer was trying to get a fine rolled seedbed to negate the effect of slugs (I can appreciate that).  Secondly the cultivations were up and down the slope, very practical from a working point of view but it gave the moving soil somewhere to run.  Thirdly there could have been compaction (although I didn't dig around) that might have reduced the water infiltration rate, causing more water to run off than would have soaked in.  This could also be related to organic matter content in the soil. 
I had a think and thought about what could have been done to negate an issue like this occurring at home or anywhere where we farm on a slope.  There could have been an option to cultivate across the slope; minimal tillage would have retained the trash on the surface to intercept the rain fall, slowing it down and reducing the glazing over of the soil surface.  I also thought about a buffer strip along the bottom headland to intercept any further erosion before it enters the water course.  This year has been exceptional from a soil management point of view and we hope that years like this aren't too frequent but we have a role to play in keeping out biggest asset (soil) in the field at all time.  It's also through years like this that we learn about where our issues lie and then we have to think about how we go about solving them for the future.  There are some very real practical tips in this LEAF Simply Sustainable Soils booklet with further information on how to avoid finding yourself in a situation like this.

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