Vermont springs and summers are as variable as ever. While rainy spells make raised beds a preferred option,, the growing season is just as likely to have prolonged dry hot periods where irrigation is necessary to keep plants from experiencing heat and water stress. Whether wet or dry weather, well-formed raised beds enable farmers to have more control over moisture. Benefits of raised beds:
- Roots of your transplants won’t get wet feet in saturated soils,
- Growing area delineated so plant damage and soil compaction avoided,
- Elevated soils warm earlier in the spring,
- Variety of implements can be used to make raised beds, including a walk-behind tractor.
With wetter weather on average, raised beds drain more quickly after heavy rain events, which is especially useful for some Champlain Valley soils that have a high clay content. And then during extended dry hot periods, drip tape under mulch keeps soil moisture levels up.
The National Weather Service’s Climate Prediction Center gives three-month outlook for precipitation and temperatures. In recent years, the Northeast has been showing higher than normal temperatures, resulting in soils drying out faster so demand for irrigation is growing but farms need to make sure there is a sufficient water supply so drawdown on wells and groundwater is not a problem. Intervale Community Farm has found that their irrigation system not only avoids crop losses of lettuce and other greens during extended dry periods, but also ensures higher quality vegetables, without signs of stunted growth (e.g. stubby carrots).
Spring soil preparation – scale makes a difference
Farming intensively on less than an acre, Shakey Ground Farm can’t justify the implements to plant and manage cover crops. In the fall, farm manager, Drew Slaubaugh, uses a 24-inch walk behind Troy tiller to make two-foot beds with a V-shape furrower, leaving a two-foot walkway and managing to keep tires in the same line. For cover to protect soils and keep weeds at bay, Shakey Ground lays down heavy reuseable plastic in the fall. Come spring, the black plastic has kept the soil dry and warmed it up more quickly so planting can begin in April for cool weather crops like kale and spinach.
Cultivating about 12 acres of vegetables, Dave Quickel, owner of Stony Loam Farm, has invested in a number of implements to manage green manures and prepare his soils. Almost all his fields are cover cropped during the winter, and in the spring, several implements are used to prepare the soils including plowing in the cover crops and tilling and mixing in poultry manure. Stony Loam cover crops mostly with rye, which has a high carbon to nitrogen ratio, so poultry manure is needed to improve nitrogen levels. Once the green manure is mixed in and soil is tilled, Dave uses a dedicated bed former to shape his beds.
Other farmers use roto-tillers, spaders, and different types of discs and cultivators to work their soils. Soil preparation is different depending on the soil structure and texture, with a bed former working best for soil with uniform aggregate size and reasonable tilth.
Stoney Loam’s mulch layer lays down four foot plastic and attached discs throw soil on the plastic edges to keep it in place. This creates a three-foot wide bed. The beds are crowned, higher in the center so water runs off more easily. The plastic mulch keeps weeds at bay and the black color absorbs heat, warming up the underlying soil. This mulch layer implement also lays the drip tape underneath. Over recent years, Dave has been pleased with his mulch layer, which he bought second-hand for less than $1000 (new these units cost about $2000+).
Newly-formed beds need a week or two for the soil to settle before planting. The bed former and plastic mulch layers to shape and cover raised beds and down drip tape in one pass are proving popular. But compared to a bed former alone, the price tag starting new at $2000 ranging up to $5000+ can be prohibitive.
These implements can be attached to the 3-point hitch on a tractor but the size needs to be compatible with the power of the tractor. Whether purchasing this equipment is the right decision depends on a number of factors: the amount of land cultivated, the time available for soil prep, the equipment already on hand and how it can be adapted to the soil and field prep given the cover crops. Actual usage and storage and maintenance practicalities should also be considered. It may well be more cost effective to hire a custom operator with the necessary equipment and skill to prep soils and make the beds once a year. Ideally, you’ll want to test a bed former and mulch laying equipment before purchasing and ask:
- Is the size compatible with your tractor and three-point hitch?
- Can you hitch it on your tractor easily enough?
- How adjustable is the height and width of bed former?
- Does it make the right size beds for your row configuration?
- How are the discs aligned? Are they throwing in enough soil for the beds?
How much time and how many passes you make in the field depends on the type of cover crop mixed in, the specific implements in use, the soil, the the operator skill, and the weather. Finding the balance between enough soil prep and too much requires a fair amount of finesse. Too many passes in the field can damage soil structure and cause compaction; too few and weeds remain and outcompete crops. Alternatively, some cover crops can be harvested and ways of protecting soil health with low tillage can be explored. For more information on cover crop management, check out UVM Extension’s Northwest Crops and Soil’s program and talk to UVM Extension’s Crop, Soil and Pasture team..
Suzy Hodgson, UVM Extension, Center for Sustainable Agriculture