Three paths for fertility, seeding and weed control

                                                                                                Eric Wegner                                                                                                Engr. 420 The current situation at the organic farm involves substantial off-farm inputs for water and fertility (500,000 gallons of aquifer water for irrigation and several truckloads from the WSU composting facility for fertility) as well as substantial hand labor for weed control.  The soil is prepared for planting with a spader, usually followed by a rototiller.  Tillage operations dry the soil, increasing the need for irrigation, and break down soil organic matter, offsetting the benefits of compost applications.  This proposal deals with three alternative methods for fertility/water/weed management that could reduce inputs, improve soil organic matter and help control weeds. The first path involves an alternative fertility input as a combination water conservation and weed control strategy.  Alfalfa hay is rich in Nitrogen (75%) and can be processed on site to make a slurry mulch which would deter weed growth and decompose into nitrogen rich compounds and other, more stable, organic matter.  The process would involve using small bale alfalfa hay run through a forage chopper along with some binding material such as recycled newsprint to make a slurry which would be spread in a row two inches deep.  Transplanted crops, such as brassicas, could be planted directly by hand through the mulch soon after application.  Potatoes could be laid in a narrow trench and covered prior to application. Other crops, such as corn, might be able to have the slurry applied post emergence.  Pre-planting preparation would involve only mowing to mulch weeds and crop residues.  Avoiding cultivation can reduce water loss to evaporation by an estimated half inch per operation.  Fertility is harder to estimate, but a typical small bale should reduce to cover a row 2” deep, 30” wide and six feet long, and with a typical weight of 80 lbs, would provide around 52 lbs. of N.  Most of that would not be available to the crop during the growing season, and a majority of it would decay before the next season, but some would leach into the root zone the first year, and more would be available the second year after incorporation. The second path involves a no-till seeding approach, which would be more appropriate for larger crops such as corn, squash, or melons.  This would involve planting a green manure crop the previous fall, such as Austrian winter peas, then mowing the crop down as close to the dirt as possible in the spring just prior to planting, followed by a V-sweep plow and air seeder, possibly with a starter fertilizer added just below the seed level.  The Austrian peas will provide some competition for weeds over the winter, but more importantly will provide around 80 lbs of N per acre as they are broken down in the soil.  The V-sweep plow cuts the peas and any remaining weeds off at one inch below the soil surface, which then forms a soil-mulch layer under the additional mulch of the shredded peas.  Seeding is done in the same pass as the V-sweep with an air seeder, which delivers the seed to a depth just below the soil mulch layer, and can add some starter fertilizer at the root zone at the same time. The third path involves conventional seedbed tillage for crops too small to manage by the previous systems, such as carrots, beets, lettuce or spinach.  Although a fine seedbed is worked up, the soil is covered with a protective layer of heavy kraft paper, through which is planted the seeds by way of a puncturing seed inoculation system.  The small seeds are mixed in a runny paste of corn starch and water, and injected through a puncturing mechanism through the paper mulch.  Liquid fertilizer (fish emulsion or seaweed extract) may be used with the corn starch mixture.

Comments

[Danny Tappel]

You have 3 very good ideas presented, so I will try to comment on them all, and this might make for a long post. First of all, I like that these are easy to implement on the farm, they use simple materials, and the processes and the reasoning behind them are straight forward and logical. Incorporating alfalfa in the first path is a good way to ensure ample N content in the soil, which the speaker (I forget her name) said was usually the limiting factor in plant growth. However, only covering a 6' long strip of crop per bale will get costly very quick, unless we have a cheap way to produce alfalfa on site or receive donations from local farmers. I am wondering if 2" deep pass is necessary, or if the slope of the ground will make that deep of a sludge run down hill. Would 1/2" be enough? While this would allow only 1/4 of the N, that would allow less running down hill. Maybe multiple 1/2" passes would allow the sludge enough time to dry so the next pass could be laid on top without running, and could eventually build up to the 2" thickness. I am also wondering if being more precise in the laying down of the sludge would help. I know plant roots grow out horizontally, but maybe each row of plants could have a specific width of sludge applied to the top. Does the nitrogen disperse when it gets down into the soil like water does? This might save resources. Also, you say most of the N will decay before the next growing season, you obviously know more about this than I do, but is this because the sludge is open to the atmosphere, or would it naturally decay that quickly even in the soil? Are there any other ways to get alfafa (or any other nitrogen rich product) cheaper, or utilize less per pass? Maybe if fertility drops off after 2 years, you could do half the farm one year, and half the farm the next, in somewhat of a crop rotation?

In the second and third path, it seems like you are trying to replace hand planting by tractor planting, while also eliminated weeds (correct me if I'm wrong). The second path is straight forward, the only thing we would need to do is find some way to get the seeds into the soil. The third path is also very ingenious. I forgot, was the kraft paper for weed control? From the pictures you posted on this subject, it seems like each pass of the tractor was a few feet wide. It seems like a waste of if each row was this wide, so would this translate to multiple rows being planted in one pass? This path also requires some way to get the seeds into the soil, and it might be a good idea for the weed seeder to be able to plant both big seeds and small seeds. Both big and small seeds need to get into the soil, and so a dual-action seeder = multiple uses = good!

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