Use of cover crops is becoming a common practice among vegetable producers. Cover crops provide multiple benefits such as building of organic matter, erosion and weed suppression, nitrogen fixation, and improvement of soil health. Cereal rye is the most widely planted cover crop in Iowa, however, cover crops such as oats, oilseed radish, and clovers are gaining popularity. The goal of this project was to evaluate and study three fall-planted cover crops and their effect on spring-planted potato. The three cover crops studied were Cereal Rye, Oilseed Radish, and Crimson Clover.
The sandy soils of Muscatine County, Iowa, are prone to erosion and leaching. In the fall, leftover fertilizer applied to the corn and soybean crop is highly susceptible to leaching. Cover crops have been widely acclaimed to mitigate such issues as they prevent erosion and scavenge residual nitrogen. Although these attributes are widely known, adoption of cover crops has been slow. Information on cover crop planting dates, performance, and advantages are available, but few data are available that is applicable to Iowa soils and growing conditions.
The use of tillage is widespread in organic vegetable production, due to its importance for cover crop incorporation, seedbed preparation, and weed control. However, its harmful effects on soil health have spurred interest in systems that reduce the need for tillage. Because nitrogen is often limiting under high residue/reduced tillage conditions, fertilizer management is considered key to crop productivity.
A wide array of information is available on cover crop selection, planting date, and potential advantages, but very little data is available on cover crop performance under Iowa growing conditions. In order to expand cover crop options for Iowa growers, more precise and region-specific information is needed.
Bok choy, also known as pak choy or pac choi, is a leafy vegetable that belongs to the mustard family. It is commonly referred to as ‘chinese cabbage.’ Bok choy is a non-heading form of Chinese cabbage and has thick white or pale green leafstalks (petioles). Leaves are dark green in color but there are cultivars with red leaves as well. Chinese cabbage is a cool-season annual vegetable and is grown by a number of vegetable growers in the state. The crop grows best with short days and moderate to cool temperatures (60 to 70 degrees F mean temperature).
Growing muskmelon in a more sustainable way involves multiple management practices. Cover crops often are incorporated into the soil before planting the cash crop. However, they also can be “rolled” and used as a ground cover throughout the growing season. The cash crop is planted in small, tilled strips within the residue. This “strip-tillage” technique provides a weed-controlling, moisture-retaining mat that does not need to be removed at the season’s end, as plastic mulch does. The reduction in tillage can improve soil structure and health.
The objective of this trial was to evaluate the use of Greenshift plastic mulch in a lettuce production system.
Sustainable production of summer squash involves multiple management practices. Some cover crops can be “rolled” when mature to produce a ground-covering mat. The cash crop is then planted in tilled strips made in the residue. This “strip-tillage” technique provides a weed-controlling, moisture-retaining mat that is biodegradable, unlike plastic mulches. The reduction in tillage can improve soil health. Row covers provide a favorable microclimate and act as a physical barrier to pests when placed over young transplants.
Biochar is an organic amendment produced by the process called pyrolysis, which is the burning of biomass in a limited oxygen environment. It can be produced using different biomass types, for example, switch grass, corn residue, or hardwoods. Potential benefits of biochar in cropping systems could include nutrient recycling, soil conditioning, and long-term carbon sequestration. Research in corn and soybean production systems has shown promising results with biochar application, however, research in vegetable cropping systems is lacking.
High tunnels are plastic-covered, passively ventilated and heated structures where crops are grown directly in soil. They have become important tools for Iowa specialty crop producers to increase production of quality crops, extend the season, and increase profitability. The environment in a high tunnel, without rainfall, limited space, and potential climate control requires a unique set of crop management skills. High tunnel production is primarily dominated by tomatoes. Interest among growers focuses on year-round production in high tunnels.
At the 2012 Fruit and Vegetable Field Day held at the Iowa State University Horticulture Farm, Ames, Iowa, one of the major challenges highlighted by commercial vegetable growers was “weed management.” Growers called for research on sustainable and environmentally conscious (less herbicide) ways of weed management. Use of cover crops to suppress weeds was one of the outcomes of the discussion. The goal of this project was to evaluate and study what advantages exist under Iowa growing conditions for four cover crops to satisfy farmer’s goals.
High tunnel production is increasing in Iowa as they provide protection from wind and frost and help extend the growing season. Although production aspects inside high tunnels are similar to field production, high tunnel environment is challenging especially when it comes to temperature management. During summer, temperatures rise fairly quickly in high tunnels and can detrimentally affect crop growth and development. It is not uncommon to see temperatures above 100 degrees F inside high tunnels.
With growing demand for fresh and locally grown vegetables, growers are capitalizing on techniques such as the use of high tunnels for season extension. After a long duration crop such as tomato, planting a quick turnaround crop in high tunnels is a viable option to continue production and increase profitability. High tunnels are an excellent resource for early spring and late fall production of leafy vegetables such as lettuce. Use of plastic mulch as a weed management tool is common in field vegetable production.
Environmental concerns and the price of fossil fuels have encouraged research on technologies to utilize biomass in energy production. Some technologies being investigated for their potential to provide energy involve a process known as pyrolysis. One of the byproducts of pyrolysis is called biochar. Biochar has shown potential to improve plant and soil health on several unproductive soils around the world. Much of the research on the use of biochar in Iowa soils has been focused around agronomic crops with little research into how it may affect vegetable production systems.
Lettuce emergence rate, seedling growth, and head size has been shown to positively correlate with seed vigor. Seed treatment practices in lettuce that increase seedling shoot mass can significantly influence lettuce growth, development, and final yield. This study investigated effects of lettuce seed treatment with Seed Power® (a nutrient solution containing cobalt and other proprietary compounds; Stoller USA) on lettuce seed germination, crop growth, yield, and potential interaction of Seed Power® with commonly used conventional fungicides.
Cucumbers (Cucumis sativus L.) are high yielding summer vegetables but are extremely frost-sensitive. Most vegetable growers in Iowa grow cucumbers and constantly explore ways to start the crop early in the spring. One method to extend the production season and start early production of cucumbers is using a high tunnel. A high tunnel helps protect plants from early season frost, warms the soil, increases ambient temperature, and enhances crop growth. High tunnel production is gaining popularity in the Midwest.
Sweet potato, Ipomoea batatas, is a warm-season vegetable crop that is widely grown throughout the world. In the United States, commercial production is mainly in the southern states. Many parts of the plant are edible, including leaves, roots, and vines. Tender leaves are a delicacy in a number of Asian and Southeast Asian countries. To grow successfully, sweet potatoes prefer both warm days and nights. Sweet potato plants require a long frost-free growing season to mature large, useful roots.
One of the biggest challenges which Midwest vegetable growers face is the unpredictable weather and narrow seasonal window for crop production. The risk of frost damage and low soil and air temperatures during the growing season are major constraints. Strategies that help extend growing seasons are thus imperative for successful production of fresh and quality produce. With growing demand for fresh and locally grown vegetables, growers could capitalize on techniques such as the use of high tunnels, low tunnels, or a combination of both to extend the growing season.
There is a growing interest among growers to utilize production techniques that reduce soil erosion, minimize nutrient leaching, suppress weed emergence, and build soil quality and organic matter. Cover crops are now being widely used by both conventional and organic growers to accomplish these tasks and also to maintain high soil fertility.
Biochar is an organic amendment produced by a process called pyrolysis. Pyrolysis is the burning of biomass in a limited oxygen environment. In the recent past, agricultural use of biochar has been steadily increasing and attracting research interest. Biochar has been shown to reduce leaching of critical nutrients thereby providing greater soil availability and crop uptake. Potential use of biochar in cropping systems could include nutrient recycling, soil conditioning, and long-term carbon sequestration.
Sweet potato, Ipomoea batatas, is a warm-season vegetable predominantly grown in the southern part of the United States. In recent years, its production region has expanded quite rapidly to various Midwestern and Eastern states. Growing sweet potatoes in Iowa could be challenging especially due to the short growing season. The crop requires a long frost-free period and high soil and air temperatures to produce quality roots. Growing this crop on raised beds with plastic mulch could be an alternative technique as plastic mulch warms the soil and accelerates crop growth.