Source: Sustainable Conservation
Conservation tillage (CT) is an umbrella term used to describe several methods that decrease the number of tillage passes through fields, saving fuel and labor, while increasing organic matter and improving soil tilth. These tillage methods range from no-till — where subsequent crops are planted directly into previous crop residue — to strip-till, where only a four-inch strip is tilled for a seedbed. Dairy farmers in the San Joaquin Valley are now adopting conservation tillage in increasing numbers because of operational efficiencies, lower costs, and potential water savings.
Pioneering dairy producers who recognized the benefits of CT have mostly worked out the kinks, and are successfully farming thousands of acres in California. As strip-till, the most popular form of CT gains in popularity, the market has responded with an increased availability of implements. Precision technologies built into strip-till units and planters have improved the ability of farmers successfully operate in conditions with high crop residue and limited tillage. Experienced CT farmers and a small but growing group of agronomists now share their experiences with novice producers interested in making the transition.
Adoption of CT isn’t as simple as swapping one field preparation method for another. Early adopters of conservation tillage in California learned quickly that successful CT demands incorporation of a complete system in your fields. Timing of different operations throughout the growing season has a significant impact on yields and quality of crop. Important issues that must be considered to achieve success with CT include an understanding of field requirements, possible changes to irrigation management, and the right equipment. Note also that the genetic traits of specific varieties could also be an important consideration, but the following tips are focused on issues related to land preparation and crop management.
1. Field must be level, but with a slope requirement — A level field is necessary in order to maximize even distribution of flood irrigated water across the field. Strip-till corn is planted on flat ground without the advantage of furrows that channel irrigation water across the field in conventional tillage systems. Uneven sections of fields are a typical source of lower yields due to poor seed emergence and development, and weed competition. Water logging and high weed populations in low lying areas, and dry soil in higher sections of fields are typical problems to be avoided by grading your field before transitioning to strip-till. The gradient, along with a well designed tail water return system will allow for an efficient movement of flood irrigation water across the field.
2. Field borders should be correctly established — In a strip-till system, field borders are typically wider and gently sloping with a higher apex in order to better control irrigation water. This design allows for planting of corn on all available land including the gentle slopes of the berm. It is critical that the distance between field borders on opposite sides of the field be accurately sized in order to fully accommodate complete implement passes between borders without breaching the apex on either side. When transitioning to a strip-till system, it is best to set up field borders in the fall prior to planting winter forage.
3. In-furrow starter fertilization is recommended — The plan may change from year to year, but the fertilization schedule still has to fit in with tillage and planting schedules to achieve the goal of fewer passes. Applying a starter fertilizer in-furrow as a side dress and below the root zone in addition to surface application of nutrient rich manure water will help ensure a vigorous stand establishment. The presence of large amounts of crop reside typical of strip-till fields have the potential to limit nitrogen availability, especially during the first year of making a transition. Researchers have also suggested a relationship between glyphosate Roundup Ready herbicides and micronutrient deficiency. It is therefore important to conduct regular soil testing in order to stay one step ahead.
4. Irrigation requirements will likely change — Water management is key. Irrigation scheduling on CT fields is slightly different than with conventional fields and the timing of each irrigation is very important. Moisture management in a CT system can make or break the crop and must be closely monitored. Growers transitioning fields to CT may find hard, compacted soils a challenge at first. Growers with several years of CT experience have data showing their fields are using less water to produce a crop and intervals between irrigations are longer due to the increased moisture holding capacity of the soil. It won’t be that way at first. Irrigation on no-till fields occurs 3-5 days sooner than the strip-till field.
5. GPS-RTK implement guidance system — Because consistent seed placement is vital to vigorous plant development in a strip-till system, the use of global positioning system technology ensures that both the strip-till implement and planter are tilling and planting the same in all sections of the field. Standard GPS signals can often have delays that can cause inaccuracy in seed placement. Conservation tillage advisors recommend using Real Time Kinetic (RTK) guidance system to enhance accuracy of seed placement.
6. A systems approach is key in successful weed management — Timing herbicide applications with crop germination and irrigations requires advance planning. Also essential to weed control is some knowledge of the amount of weed pressure in the field. Depending on weed pressure, experienced CT growers will apply herbicide a day or two ahead or a day or two after planting. This allows the corn plants to get a head start on weeds. Another 10-12 days after corn plants emerge, an irrigation will germinate remaining weeds which can be sprayed with herbicide at the same time a miticide is needed in the corn. Having access to a spray rig on the day it is needed is another important component. Growers report that an ATV sprayer with a boom helps avoid compaction issues when applying herbicide. With the current drought conditions, more growers are planting sorghum silage, a crop that does not have roundup ready capability. However, sorghum competes well with weeds and a pre-emergent spray does a good job. Again timing with irrigation is critical as herbicides can be less effective on water stressed weeds. Use of a hooded sprayer is valuable when applying herbicide between rows.
7. Planter retrofits will be needed for tougher field conditions — Achieving consistent seed placement may call for some planter retrofitting. Depending on soil type, moisture and amount of crop residue, proper adjustments need to be made to ensure precise seed placement. Experienced CT growers use down pressure springs/airbags to maintain positive contact with the ground. Crop residue and hard packed ground between the strip- till furrows can make the planter ride a little rough and seeds may not be delivered to the right soil depth or receive enough firming for proper soil contact.
The seed firmer is another technology that is not exclusive to CT, but it helps give seed a better start when dealing with a more complex seed environment. This tool is attached to the planter between the disk openers and drags across the bottom of the trench. The seed is dropped in front of the firmer which presses it into the soil. Planter modifications can also be made to add clearing wheels or sweeps to remove some residue from the seed zone. Where sub-soiling is required, splitter points can replace standard ripper points to reduce upheaval at the soil surface. Sub-soiler shanks can reduce buildup of soil that can drag residues.
8. Managing soil compaction becomes easier as your soil rebuilds itself — Keep in mind that while transitioning to CT, soil compaction may be a challenge. Fields intensively tilled over for many years usually undergo multiple field passes which result in a breakdown of soil structure and loss of organic matter. As a result, it is not unusual to find many farmers with very hard and easily compacted soils, and who believe that only regular ripping and aggressive tilling work on their soil types.
Different soil types will require management styles adapted to their specific conditions, especially during the first two years of transition to CT. Timing irrigations on harder soils is one of the first steps toward overcoming compaction issues. Over time, fewer field passes will yield more resilient soils that can “bounce” back instead of compacting. Growers who made successful transitions to CT said the reduction in field passes begins the process of building soil. Lighter tractors, flotation tires on harvest trailers also reduce compaction. Typically, harvest time is when the most field traffic occurs. Growers recommend timing the last irrigation so the ground is dry enough to support equipment.
9. Conduct regular soil testing — Noticing changes in their soil during the transition to conservation tillage, growers appreciate the healthier structure and moisture holding capacity. Whether using dairy nutrients or chemical fertilizers, a regular soil testing program will help ensure your nutrients are meeting the needs of your crop. Testing helps growers become aware of soil balance. Monitoring the composition of soil helps with decisions about nutrients and soil pH. With dairy nutrients, high levels of P and K can develop, tying up availability of essential micronutrients and limiting crop yields.
10. Heavy tillage or ripping after CT could set you back — After a successful first season of growing corn with a CT system, going back to conventional tillage for your winter crop will be a setback for soil recovery. In order to maintain the soil benefits of strip-till, you should actively consider using a no-till drill for your winter rotation. This initial transition should be carefully managed to make sure that your soil organic content and structure has developed enough resiliency for this next step. It may be necessary to do some limited tillage or ripping during the first couple of seasons, so testing for soil compaction is important. Remember that recovery of your soil to a healthy state after years of aggressive tillage takes time and patience.
If you are interested in trying CT, California Ag Solutions and Sustainable Conservation? have partnered to provide Central Valley dairy producers and silage growers with a low cost option for evaluating a strip-till system. Mikel Winemiller of California Ag Solutions and Ladi Asgill of Sustainable Conservation will work with growers to evaluate a field for a strip-till system and arrange delivery and setup of CT implements on your tractor. They will also provide season-long agronomic support. The technology requires use of GPS with RTK service on your tractor in order to allow precise seed placement.