Crops mulch

Allelopathic interactions of plants can provide weed control by (a) use of allelopathic crops as cover crops, mulches or green manure, (b) use of allelopathic plants in crop rotations, (c) crop mixtures and intercropping, (d) varieties with strong allelopathic potential, and (e) use of allelopathic crop water extracts and other agents. 

Hutchinson, C.M. and McGiffen, M.E. 2000. Cowpea cover crop mulch for weed control in... 

Teasdale, J.R., Abdul-Baki, A.A., Mills, D.J. and Thorpe, K.W. 2004. Enhanced pest management with cover crop mulches. Acta Horticulturae 638 135-140. 

It is well known that crops mulched with transparent film produce more than unmulched crops or crops mulched with opaque film. The lower concentration of nitrogen found in plot F is due to the higher output of vegetables and roots which means higher nitrogen uptaking from the soil by the crop. The lower... 

Cultivation of soil has and will continue to be an important means of controlling weeds (1). However, extensive soil cultivation leads to various problems such as losses of soil, soil moisture and nutrients. This results in water pollution by both the soil itself and pesticides and nutrients associated with it (2, 3, 4). Minimum or no-till cropping systems can reduce these problems because various crop residues (i.e., mulch) are left on the soil surface with a minimum of soil disturbance in planting the crop. 

The presence of crop residues has been reported to both increase (5, 6) and decrease crop yields ( 7) and not tilling to increase certain difficult to control weeds (8). However, other reports indicate that the presence of certain mulches can reduce the biomass of certain weeds (9-15) and allow for higher crop yields ( 5, 6). Thus, under certain conditions, mulches can suppress certain weed species, but determining the reason(s) presents many logistical problems, especially under field conditions. To determine the cause(s), the physical and chemical (i.e., allelopathy) effects of the mulch and the role of soil disturbance (or the lack of, as would be the case in a no-till system) must be separated. 

Even with these problems, attempts have been made to demonstrate that mulches suppress weeds allelopathically. Putnam and DeFrank (12) and Barnes and Putnam (39) used Populus wood shavings to separate chemical and physical effects of mulches. Their work indicated that certain mulches do possess allelopathic potential. Liebl and Worsham (9) and Shilling and Worsham (14) placed mulch on tilled soil, after tilling, in an attempt to provide the weeds with an exposure to light. Their work also indicated that at least part of the suppression of weeds by wheat and rye mulch is allelopathic. Thus, research to date indicates that both mulch and the lack of soil tillage contributes to the suppression of weeds in no-till cropping systems. 

No deleterious effects of either the wheat mulch or tillage were observed on soybeans (Table V) or corn (data not presented). In general, crop growth was better in mulched or no-till plots. Enhanced soil moisture in the mulched treatments and reduced morningglory densities in the non-tilled treatments may have contributed to improved crop growth. 

Study 2. The effects of wheat, oats, barley and rye mulches on three broadleaf weed species and crabgrass (Digitaria spp.) are shown in Table VI. Weed control data for the corn test at Kinston are not presented because of poor cover crop kill by the paraquat treatment. 

Table VII. Mean broadleaf weed control of mulched and unmulched treatments averaged over location, crop, and weed species...

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