- Vegetables: cucurbits, tomatoes
- Crop Production: cover crops, nutrient cycling
- Pest Management: allelopathy
- Production Systems: general crop production
- Soil Management: green manures, soil analysis
A comparison of various cropping systems suggests that cover crops could improve vegetable production under short-term crop rotation. Integrating cover crops into short-term vegetable crop rotation improved soil fertility, reduced weed population, increased soil microbial activity, and enhanced cucumber and tomato yields. Use of legume cover crops like hairy vetch or cowpea showed potentials to help reduce nitrogen fertilizer inputs in subsequent crops. A cropping system that includes cover crops would improve the long-term viability of the farm while protecting the environment from nutrient leaching.
Intensive vegetable production is generally achieved by high fertilizer and pesticide inputs in order to meet the ever growing market demand for quality produce. There is a wide variety of vegetables produced in Michigan (Michigan Department of Agriculture, 2006). Michigan is ranked first in the U.S. for processing cucumbers and fourth in the nation for fresh market cucumbers (Michigan Department of Agriculture, 2006). Over the years, it has become increasingly difficult for growers to maintain high yields and quality. This can be attributed to factors such as increased incidence of soil-borne diseases, weed pressure, reduction in soil fertility levels, limited availability of good land, and economic constraints. Over the past few years, Michigan vegetable growers have been interested in adopting sustainable agronomic practices which can serve a two-fold purpose: cost reduction and quality improvement. Most vegetable growers understand the benefit of long-term crop rotations. However, lack of good land and the need for crop specialization has forced them to adopt short-term rotations. Cover crop usage is well documented and its benefits include: erosion control, reduced runoff, improved infiltration, soil moisture retention, and improved soil tilth, (Blevins et al. 1990; Hall et al. 1984; Robinson and Dunham 1954; Teasdale 1996; Teasdale and Mohler 1993; Utomo et al. 1990). In addition, cover crops can also provide weed control (Gallandt et al. 1999; Mohler and Teasdale 1993; Ngouajio et al. 2003; Teasdale and Daughtry 1993; Williams et al. 1998), and improve soil fertility (Kuo and Jellum 2002; Kuo et al. 1997; Ranells and Wagger 1996). In Michigan, cucumber – tomato rotation is a common rotation followed by vegetable fresh market growers on an intensive scale. Because of the short growing cycle of cucumber, harvest is usually completed by Mid July, allowing a short window for growth of summer cover crops such as sorghum sudangrass [Sorghum bicolor (L) x S. sudanense (P) Stapf.] and cowpea [Vigna unguiculata (L.) Walp.]. In addition, both tomato and cucumber could allow planting of winter hardy cover crops like cereal rye (Secale cereale L.), and hairy vetch (Vicia villosa) after harvest of a cash crop. Management practices that include cover cropping have been reported to affect soil quality parameters (Gregorich et al., 1996; Kou et al 1997). Cover crops provide increased vegetative cover, facilitating reduction in soil erosion levels and enhancing soil C and N levels (Kuo et al., 1997). Fall seeded winter cover crops especially, cereal rye, are the most commonly used cover crops in Michigan (Ngouajio and Mennan, 2004). They are planted in fall after cash crop harvest and killed by cultivation or herbicide application in late spring (Mutch and Martin, 1998). Rye has been shown to increase soil organic C and N (Kuo et al., 1997) as well as impact weeds and disease levels in cropping systems (Bottenberg et al., 1997 a,b; Ngouajio et al. 2003). Cover crops may also increase tomato yield as compared to a bare ground fallow system (Shennan, 1992). Legume cover crops such as hairy vetch has shown enhanced soil N levels as well as increased tomato yield in comparison with systems with no cover crop inputs (Teasdale and Abdul-Baki, 1995; Sainju et al., 2001). Legume cover crops also increase soil C levels and improve tomato shoot and root growth (Sainju et al., 2000). If cover crops were successfully integrated into short-term tomato-cucumber rotations, they could improve the cropping systems with minimal change on growers’ practices. Our general goal was to integrate warm season (summer) and cool season (winter) cover crops into a short-term tomato-cucumber rotation.
Project objectives:div style="margin-left:1em;">
- Evaluated the effectiveness of summer and winter cover crops at improving soil fertility under vegetable production systems.
Measure the effect of the cropping systems on soil microbial activity.
Determine the effects of cropping systems on weed populations.
Quantify the effects of cropping systems on cucumber yield and yield quality.