Monday, March 8, 2010

Spring Training-To Till or Not to Till

I mix batches of COF (complete organic fertilizer) from a list of ingredients including fish meal, seed meals (canola, linseed, alfalfa, etc), lime, dolomite, gypsum, green sand, glacial dust, rock phosphate, azomite, fish bone meal, and kelp meal to use in my garden every time I plant. These ingredients are not usually found in garden centers. I happen to be fortunate to live close to a wholesaler that specializes in supplements for the organics industry. You need 4-6 quarts per 100 sq ft. of bed or 50 feet of 18” wide row with a plant in the middle. Bagged fertilizers don’t have near the mineral and micronutrient content and may contain large amounts of arsenic, especially if it was sourced from commercial poultry operations. I mix two different blends, one for lush green growth and another for fruiting vegetables. Leafy greens like more nitrogen but with tomatoes and other fruiting plants that will just get you a huge plant with little or no fruit. Many soil scientists at land grant colleges like Oregon State University’s chief soil scientist, John Hart, don’t believe anyone should bother with the time and expense to add minerals to their soil and that the only important thing about food is that it should be competitively priced with produce grown by commercial farms in Mexico, Chile, and China. Maybe you understand my unending tirade against the USDA and how land grant colleges are funded (mostly by corporate interests). Since most family farms aren’t a good model for taxation there is no interest at Congress to support them.

For those of you getting your rototillers out, it may be too early to till, especially if you have clay soil. To see if you should be tilling, brush aside the organic matter on the surface to dig out a clump of soil. Squeeze the soil, without any organic matter in it, into a tight ball with both hands. If the ball breaks apart when you drop it on hard ground from waist level then you should be ok to till. If it mostly just goes splat, tilling will compact the soil and join the clay particles together like glue. If there is no soil line visible below the organic matter at the depth you would be tilling, generally 6-8”, then you might not need to till at all. This generally means that your soil is humic and tilling will just kill off most of the living organisms in the soil, the vast majority of which are beneficial to your plants, and you will end up with a net reduction in the amount of organic matter.

Tilling isn’t something that I recommend doing very often and usually only when you are breaking new ground and need to chisel through stuff that hasn’t been maintained well. The one exception is if you are growing green manures that you need to incorporate into the soil. Depending on the green manure you should be doing that at least two weeks ahead of planting and more if you are seeding rows with a row seeder. Once your beds get established and have adequate organic matter, 7-10% by weight, all you want to do is gently aerate the soil every year just before planting. When you till, it generally creates as many problems as it solves.

You might not need to wait weeks or months to be able to get out and till the garden. Sometimes it just means getting a few days in a row of no rain. If you don’t have enough organic matter on the soil or plants to break up the impact of the rain on the ground, then successive rain storms could compact the ground back to the way it was before it was tilled. This might leave you worse off than if you had done nothing because the tiller will break up whatever humus is already in your soil and burn up some of the organic matter by exposing it to oxygen. Even if you have deep organic matter in your soil you should test down as deep as the tiller will go to make sure that you don’t create a hard pan.

It’s best to wait until it is closer to time to plant to till the soil unless you are turning in green manure. That way the soil will still be a nice planting bed. You want to add at least 2” of organic matter to your beds each time you clean off the last crop and that can sit on the ground until you are ready to plant. You can till some organic matter into the soil and then cover it with some more to protect it from the rain. It will feed the soil and increase the biological activity while suppressing weeds. The weeds that do come up will be easier to remove because the organic matter will help loosen the soil. I get compost for $20 a cubic yard which is the capacity of those little $300 trailers you can buy as a kit in most large hardware stores. Instead of buying bags of compost for $3-5 a bag, maybe you know a couple of people that would like to split some yards of compost/soil mix for the same price you would pay if you were buying it by the bag? You would get a lot more bang for your buck and maybe get a little needed exercise will mean that you use less water and have a nicer garden with fewer weeds and you can relax more this summer when it gets really hot.