There has been considerable activity in breeding orchardgrass (Dactylis glomerata L.) cultivars in North America during the latter half of the 20th century, but little effort devoted to quantification of breeding progress. The objectives of this study were to quantify changes in mean cultivar performance for that time compared with the progress achieved from one cycle of half‐sib progeny selection within the USDA population of orchardgrass accessions. Forty‐two cultivars (32 North American cultivars and 10 European cultivars) were tested at three locations (Arlington, WI and Rock Springs, PA, and Ottawa, Ontario, Canada) in 1995 through 1997. Cultivars were grouped into three experiments by maturity class: early, medium, and late. North American cultivars averaged 3, 9, and 12% higher in forage yield than European cultivars for early, medium, and late maturity groups, respectively. Between 1955 and 1997, forage yield and ground cover of early‐maturity cultivars increased by 2.5 Mg ha−1 decade−1 and 4.0% decade−1, respectively. Forage nutritional value of medium‐maturity cultivars increased during that time, although this was probably not due to direct selection. Significant gains were made in forage yield and Drechslera spp. leafspot reaction of cultivars derived from two individual breeding programs, although the majority of orchardgrass cultivars lack improvements in forage traits.
External drainage losses of atrazine (2‐chloro‐4‐[ethylamino]‐6‐[iso‐propylamino]‐s‐triazine) were evaluated at two application rates, applied preemergent, and pre‐plant‐incorporated on a hillside where corn (Zea mays L.) was planted with and without oats (Avena sativa L.) as a strip crop at the slope base. The cropping pattern had the most striking influence on soil, water, and atrazine transport in a growing season where a 100‐y frequency storm occurred during June. Statistical covariance analysis revealed that nearly 100% of the time, total atrazine residue losses in external drainage and soil sediment were most strongly related to the number of days from herbicide application to each erosion event.The small grain strip or buffer zone reduced water and soil losses by 66 and 76%, respectively, compared with nonstripped areas, during 11 erosion events. Atrazine losses of 3.5 and 0.33% of that applied (2.2 kg/ha) were recorded in the absence and presence of an oat strip, which represented a 91% reduction in herbicide loss with strip cropping. At the 4.5 kg/ha application rate, herbicide losses were reduced by 65% in the stripped areas compared with the nonstripped areas. Minimal pre‐plant incorporation of atrazine residues with the soil surface also significantly reduced residue loss with each cropping pattern. Using nonstripped, preemergent treated areas as a reference, pre‐plant incorporation of atrazine with strip cropping reduced total atrazine losses by 91 and 87% at the two respective application rates, and allowed only 7 g/ha of atrazine loss at each rate. Therefore, a conventional tillage‐management system combining a minimal surface‐blending of atrazine residues with strip cropping provided soil, water, and chemical residue retention equivalent to that achieved in reduced‐tillage crop management and controlled weeds effectively.
Losses of cyanazine (2‐[[4‐chloro‐6‐(ethylamino)‐s‐triazin‐2‐yl]amino]‐2‐methylpropionitrile) in runoff from untilled soil planted to corn (Zea mays L.) were compared with losses from conventionally planted corn on a 14% slope in the growing seasons of 1977 through 1979. The no‐tillage systems consisted of corn planted into corn stover residue and into “living mulches” of birdsfoot trefoil (Lotus corniculatus) and crownvetch (Coronilla varia L.). The no‐tillage systems reduced runoff, erosion, and herbicide movement. For example, runoff from conventional tillage ranged from 5.5 to 22% of the runoff‐producing rainfall. Soil loss from the same system ranged from 4.4 to 32.2 Mg/ha. On the other hand, runoff from the no‐tillage systems ranged from 0.07 to 2.5% of the runoff‐producing rainfall, while soil losses ranged from 0 to 1.1 Mg/ha. Transport of cyanazine in water runoff and entrained sediment from tilled areas totaled 257.0, 16.0, and 32.7 g/ha for the respective growing seasons, which represented 5.71, 0.73, and 1.48% of the amount applied yearly [4.5 kg active ingredient (ai)/ha—1977; 2.2 kg ai/ha—1978, 1979]. In the same years, cyanazine losses from no‐tillage areas were 6.5–33.7 g/ha, 0.1–1.8 g/ha, and 1.6–3.3 g/ha at similarly applied rates. Collectively, these represented losses ranging from < 0.01 to 0.75% of sprayed levels. Using conventional tillage as a reference treatment, untilled surfaces reduced runoff from 86.3 to 98.7%, soil losses from 96.7 to 100%, and cyanazine losses from 84.9 to 99.4% over the three growing seasons. In general, the “living mulch” surfaces were more effective in retarding erosion than the corn stover residue surfaces. Corn grain yields were not significantly reduced by “living mulches” when adequate legume suppression was obtained with herbicide treatments.
No abstract
Influences of a hairy vetch cover crop and residual herbicides were examined in field corn in 1991 and 1992. Hairy vetch was seeded in mid-August and killed the following May with tillage, mowing, or glyphosate plus 2,4-D (no-till). These cover crop management systems were compared with a no-cover treatment. Residual herbicides including atrazine plus metolachlor applied PRE at three rates and nicosulfuron plus thifensulfuron applied POST at a single rate were compared within cover crop management systems. All cover crop management systems effectively controlled hairy vetch except mowing in 1992. The corn population was reduced in mow treatments containing uncontrolled vetch. Hairy vetch mulch suppressed some weeds in the no-till treatments in 1991, but more annual grass was noted late in the season with no-till into hairy vetch than with the no-cover treatments in 1992. Residual herbicide performance was similar across cover crop management systems, except for fall panicum control which decreased in some no-till systems. Unlike soil-applied herbicides, performance of POST herbicides was unaffected by cover crop management systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.