ARS | Publication request: Winter wheat/red clover intercrop response to tillage and compost amendment

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 16, 2011
Publication Date: October 31, 2011
Citation: Blaser, B.C., Singer, J.W., Gibson, L.R. 2011. Winter wheat/red clover intercrop response to tillage and compost amendment. Crop Science. 52:320-326.

Interpretive Summary: Frost-seeding red clover into winter cereals is generally considered an efficient and cost-effective method of establishment, yet information regarding establishment under different soil management practices is limited. Intensive tillage (IT), moderate tillage (MT), and no-tillage (NT) with and without compost amendment in a corn-soybean-wheat/red clover rotation were used to test the response of red clover establishment to soil management. Wheat yields were higher in IT and MT compared with NT in one year, higher in NT than IT and MT in a second year, and similar across tillage treatments in two other study years. Higher grain yield in IT corresponded to lower red clover densities at wheat harvest in one of three years. Red clover plant densities at wheat harvest were higher under NT and MT compared with IT in one year and were 41% lower with compost 40 d after wheat harvest of the same year. Red clover shoot dry matter at wheat harvest and 40 d after harvest averaged 70% higher when grown without compost in one year. Red clover plants preferentially established in the row of the wheat stand two of three years. Wheat and red clover under MT consistently performed equal to or greater than NT or IT. Producers using this intercrop may reduce tillage without affecting red clover densities and dry matter, but may sacrifice some red clover dry matter to achieve optimum grain yield.

Technical Abstract: Frost-seeding red clover (Trifolium pratense L.) into winter cereals is an efficient establishment method, although performance under contrasting soil management practices remains unclear. Wheat and intercropped red clover productivity were evaluated in intensive (IT), moderate (MT), and no-tillage (NT) with and without compost amendment in a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.]-winter wheat (Triticum aestivum L.)/red clover rotation between 2005-2010. Wheat yields were not affected by tillage system and averaged 3.80 Mg ha-1, but were 10% higher in compost amended soil compared to no compost. Red clover plant density and dry matter (DM) at cereal grain harvest averaged 127 plants m-2 and 32 g m-2 and were not affected by tillage or amendment treatments. Maximum wheat canopy light interception was attained in late May to early June and ranged from 84 to 91% and typically exceeded 77% light interception for at least 22 d. Red clover root DM increased on average 378% between wheat harvest and 40 d after harvest compared with an 64% average increase in red clover root length. Red clover shoot: root averaged 8.5 at wheat harvest compared with 11.2 40 d after wheat harvest. Producers using this wheat/red clover intercrop should expect no difference in wheat yield or red clover productivity when using IT, MT, or NT.