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| Manures should build OM the fastest but dependent upon rate and type of manure etc. Then I feel covers and growing crops for 365 d to be second due to capture of CO2 into C6H12O2 compounds....cumulative result dependent upon growing season and climate. Then crop residues coming in third. A good management system IMO uses all 3 sources, just like many do in the garden...I consider all 3 important here!
An old NT soil should become more efficient in recycling nutrients and decaying OM....so the level of maintained OM (humus) per year may be less with time....or did the original tests have more potentially degradable OM and less humus?...ie the microbes are eating more now as a population after an NT soil 'blooms'...so on those soils should we not be relying on all 3 sources of C to build/maintain OM as the soil ages/becomes more efficient?
Then we have the lab analysis vs the 'real world' soil.....most labs report OM%, some the C:N ratio but not the fractions of OM.......whereas the soil contains soluble, rapidly degradable, slowly degradable, and undegraable OM fractions....ongoing and not in a vacuum.....the same OM fractions which the plant supplies to both the soil and the cow.....rates of degradation in the soil and cow similar, but just differnt end products.
Tillage only destroys OM if the net input of OM is less than the net soil consumption (or if lab analysis changes the #s we get).....for those who struggle with this concept please Google 'Herman Warsaw' and study his methods and soil analysis and water use efficieny...vs the fence row....he made tillage work very well! Futher, nature has a uses 'tillers'....eg worms moles gophers armadillos feral hogs skunks squirrles...how quick can she repair the tillage damage they do? Or is this 'natural tillage' an important part of ecosystem function?
IMO....the problem with mechanical tillage is the disruption of aggregates and pores and insufficient ability of the soil to rebuild, in a timely manner, the aggregates and pore network for good soil tilth needed by the current crop roots. Well managed tilled soils do just that, repair themselves quickly after disturbance, nature has all the tools she needs for the 'remodel'. Poorly managed tilled soils, however, struggle to maintain tilth, nature is 'missing' one or more key components for the 'remodel'....these we have to cultivate or irrigate. How many see this concept in home gardens?...one gardener maintaining tilth with little water use while another struggles with the same...both running a roto unit?
Think 'overall tilth' IMO....not specicifally OM which is just one component of tilth. pH has nothing to do with tilth...certain elements do....then roots and microbes play a role. OM% is just a #.
My question to many here is 'how do you mesure and access soil tilth'? | |
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Organic Matter Going Down In No-Till
