>Allan Balliett wrote: > >> *Optimum tillage for annual crops, what sort of balance can growers >> look towards in light of the soil foodweb. Comments on deep tillage >> such as spaders to no-till like Groff to heavy mulching like Emilia >> Hazelip to surface cultivation such as Eliot Coleman. > >The answer here depends on where you are starting from. It's not that >simple an answer. > >Consider that you want to match the biology in the soil with the >requirements of the plant you are growing. If you want ryegrass growing >with need for fertilizer, with minimum weed pressure, and without the >need for pesticide, you need to have bacterial biomass at a minimum of >125 µg bacteria, 100 µg fungi, 20,000 protozoa and 20 beneficial >nematodes, several hundred microarthropds per m2. > >If you lack fungi in your soil, you want to till to the absolute minimum >amount, so you leave the fungi intact, living and increasing in >biomass. If fungi are fine, and you lack bacteria, then you want to >till, to bring the ratio of fungi to bacteria back into line. If you >have a well-balanced foodweb, you don't need to till, because the >foodweb will maintain soil structure. > >So, ask the question "why do you till?" > >If you till because the soil is tight, it is crusted, water puddles on >it, or it erodes easily, Mother Nature is telling you that you've killed >off the biology in your soil, and you will have all kinds of disease, >weed, and stressed plant problems until you fix that biology. You are >forced to till to break open the soil physically. Stop doing that by >letting the bactea, fungi, protozoa, nematodes and microarthropods do it >for you. They are so much less expensive than plowing. No gas, no >hired help salary, no machine repair, just have to feed them on >occassion. Feed them with cover crops or compost. Lots of variation in >foods, please, because it is diversity that is important! > >If you till to prepare a seed bed, why not direct drill? Soil too >hard? See the previous answer. No machine, ok, then just strip till >the line you are planting in, and add compost to the tilled strip so >soil life will be enhanced, and your seeds will germinate and grow >within mere days instead of weeks. > >Why do you deep rip? Your soil is compacted at 3 to 6 feet? Why is >that? Because the life in your soil has been destroyed, and then the >soil will compact when you drive equipment on it. Need to get the life >back in your soil, and you break up hardpan at 4 feet in 6 months. >Harry Hoitink has shown this happens time and again by adding great >compost to the soil's surface, and the hardpan disappears in short >order. Why plow? You just keep killing the critters you need to have >in your soil. > >Spaders disturb the soil to a much less extent than discs, or harrows, >or rototillers. OK, a one-time pass. If you spade five or six times in >fall-spring, you lose any benefit. So, it is the intensity of the >disturbance that is important. > >Consider the USDA definition of soil. I love this example, it really >points out the plowing issue. Back in the 1950's, the USDA said soil >was aerobic in the top 4 to 6 inches, and ended there, because it was >anaerobic below that depth. So, soil was only the top 4 to 6 inches. >But then in the mid- to late '70's, the attitude started to change and >by 1985, soil depth was defined as 18 inches. Aerobic to 18 inches, >anaerobic below that. In 1994 or '95, I forget, soil depth was >RE-defined, as down to 4 feet. Aaaerobic below that. Why these >changes? > >And really, how far down do aerobic conditions occur in soil? In a >NATIVE soil, in an old-growth forest, or prairie, how far down does the >aerobic zone go? We obtained soil from 12 miles deep, and found the >microbial community fully aerobic. Why does the USDA have this >definition of soil based on aerobic/anaerobic? And why could it change >with time? > >It's the kind of machine we plow with. We used mold-board plows in the >50's, in the late 70's everyone had switched to discs, or chisel plows. >By 1996, everyone was deep-ripping to 4 feet. The anaerobic level is >strictly an artefact of plowing. Aerobic/anaerobic depths have nothing >to do with real soil, they are the result of plowing and killing the >appropriate life in the soil. > >Why do you surface cultivate? Weeds. OK, may be needed, but it is >better to figure out what your weeds are telling you. And fix the >chemistry in your soil. You may need biology in your soil in order to >fix the chemistry. You may need to adjust the chemistry to help the >biology. People who say that I say that biology can fix everything have >never listened to me. Open up the closed doors in your minds, and >listen. Biology and chemistry together, along with the sand, silt, clay >in your soil determine the physics of your soil. They work together. >They all influence each other, and you have to understand that to be >able to select against your weed problems, and for your crop. So, >surface cultivation may be able to be reduced as your soil is balanced >better for your crop plant. > >Heavy mulching really helps the fungi out. The danger is that a heavy >mulch compacts if it doesn't have the life in it that you need. >Compacted mulch turns into anaerobic, putrefying organic matter and now >you are making.......what? > >Dead plants. Ok, so compost that mulch in place by doing.... what? >Apply compost tea, get the organisms into the mulch, get the air in >there, and your plants go gang-busters. So, understnading the biology >that goes along with these practices helps you understand why things >work, or don't work. > >Hope this answers your question! > >Elaine Ingham
