The following are evident from the trials comparing roller crimping to conventional tillage and weeding:
1. There is significantly less weeding in the roller crimped areas.
2. Some crops seem to perform better in the crimped areas than in the conventional tillage areas.
a. Tomatoes and chilis in the crimped areas tend to produce larger harvests but several days to a week later for first harvest due apparently to cooler early season soil temperatures. This was also true for cantaloupe.
b. Cooler season crops like kale, chard, cabbage and potatoes produce larger yield with larger plant size in the crimped areas due to cooler soil temperatures.
3. Some crops produced better yields in the conventional ‘bare earth’ cropping system. These were summer hot weather-liking flowers, basil, early season cilantro.
4. Squash has presented some problems with growth and harvest size in the roller crimped areas in the past. Part of this year’s trials was comparison between roller crimped, bare earth, roller crimped with crimped cover removed and roller crimped with a 12” tiller row in the crimped cover. It seems evident from the results, which were similar between the crimped with a 12” tilled row planted into and the bare earth, that the difficulty with squash harvest size in the past in crimped areas is mostly a matter of soil ‘looseness’ for the shallow-rooted squash plants. While it is seen that the crimped areas have smaller yields and several day later yields compared to bare earth, the roller crimped with 12” tilled area has similar first harvest dates and yields to the bare earth, while also giving better weed control in the paths and area between plants than the conventional tillage areas.
5. Soil appearance, nutrition and organic matter continue to be impressive in the crimped areas over the bare earth, especially now that three years of bare earth compared to crimping has been done in the same plots. The table below shows the differences in the bare areas to the areas that have been crimped-grown for the last three years. Each year the nutrient analysis shows more nutrients accumulating in the roller crimped areas. It is proposed that this is due to the breakdown of the cover crop that occurs over the entire growing season rather then being ‘dumped’ into the soil in the spring when a cover crop is incorporated into the soil all at one time and leaching of unused nutrients occurs. The bare areas had the same cover crop on them as the crimped areas, only at crimping time the bare areas were mown and tilled under.
|SOIL NUTRIENT||BARE AREAS||CRIMPED AREAS|
|Organic Matter %||3.8%||4.7%|
|Nitrogen Needed for Next Year lbs/acre||120||62|
These are very impressive numbers. In three years of growing, the roller crimped areas need half as much nitrogen for the next growing season and no other soil amendments. It would seem that the vegetative matter decaying on the top of the ground assists in tying nitrogen into the soil. Weed management on the crimped areas only took about 50% of the time in weeding than the bare earth areas. Crop sizes were similar in both areas, with the crimped having slightly larger crops with carrots, kale, cabbage and potatoes, and slightly larger but several day later crops with chilis, tomatoes and cantaloupe. And the bare earth weeding produced better flowers, basil and cilantro.
6. The eventual near-elimination of weeds in the growing areas was demonstrated by this year’s trials. The roller crimped areas had only one weed, sheep’s head (Tribulus terrestris), appearing in any numbers compared to the adjacent bare earth conventional weeding area, which still has a variety of weeds. These two trial areas purposely had weed seeds introduced three years ago in applied horse manure fertilizer. In the three years of using roller crimping on half of the area, the weed density and variety has been significantly reduced in the crimped areas, while increasing soil quality. Numbers and varieties of weeds in the non-crimped areas is still similar after three years.
**note: past year’s data are from a previously funded project FW11-021
Roller crimping is a method of manipulating or killing an over-wintered cover crop that kills and flattens the cover crop during the late spring flowering growth plant stage so it remains on the soil surface, making an in-place weed suppressing mulch that lays flat on the ground. There have been two years of formal trials and three years of using this technique in a trials plot area. That area was ‘seeded’ with weed seeds through horse manure in fall 2010. Half of the area has had the cover crop incorporated into the soil each spring with conventional mechanical and hand-weeding techniques used. The other half of the trials area has for three years had the cover crop crimped into an in-place mulch. For two of those years, there was no tillage done on the crimped area. This made, in 2012 and 2013, the crimped area a no-till, roller crimped growing area. In the trials in 2012, weeds on both of the adjacent crimped and conventional areas were managed with minimal weeding, only enough to ensure no weeds produced seeds. In this year’s trials, all weeds were eliminated through weeding methods until the last several weeks of the growing season.
The goals of this project were:
1. Get researchers interested in trying crimping.
2. Get interested farmers data and a project they can see.
3. Inform farmers that may not be interested about this technique.
4. Gather field data through replicated field trials with a wide variety of plant family and plant types representative of the major vegetable crops in the southwest. This data was to measure:
a. Production of each major family of vegetable crops to test suitability of crimping on various vegetables.
b. To measure if soil nutrients are different in the two different treatments: crimping and conventional cover crop incorporation earlier in the season for conventional growing methods.
c. To gather specific data on squash production with roller crimping, no-till organic farming. Gather more specific data about why squash has problems with crimping based on several years of trials by Rhoads.