Abstract Establishing native warm‐season grasses (NWSGs) can be challenging due to their small seed size and slow growth, which necessitate comprehensive weed control and minimal defoliation during the seedling year. Use of nurse crops may partially alleviate both of these issues. Two nurse crops, browntop millet ( Urochloa ramosa (L.) Nguyen; BTM) and Ray's Crazy Mix (a warm‐season diversity blend of cereal, legume, broadleaf, and brassica species; diversity mix DM), were evaluated for their potential to provide forage while reducing weed competition and enhancing NWSG recruitment. Six treatments, four non‐grazed (NG) nurse crops (BTM, DM, no nurse crop/no imazapic herbicide NNC‐NI), and no nurse crop with imazapic (NNC‐I), and two grazed (G) treatments (BTM‐G and DM‐G) were replicated four times in a randomized block design. A blend of three NWSGs was drilled 2 weeks before the nurse crop planting. Overall, BTM and DM reduced ( p < 0.05) NWSG seedling density compared to NNC‐I, but not NNC‐NI. Weed cover rating was greater in NNC‐NI (80%), followed by both nurse crops (40%), and lastly by NNC‐I (20%). Grazing between 7 and 10 weeks after planting (WAP) reduced ( p < 0.04) leaf area index by 70% just after grazing and 40% by 15 WAP. Grazing did not affect NWSG populations but did have an impact on weed cover rating at 12 WAP, where G treatments had an 8% lower weed cover than NG treatment (42% vs. 50%). With well‐timed grazing, nurse crops can produce desirable forage and contribute to reduced weed pressure but also may impose substantial competition on NWSG seedlings.
Swilling et al. (Wed,) studied this question.