Rotational Benefits of Forage Crops in Canadian Prairie Cropping Systemsстатья из журнала
Аннотация: Including perennial forages in cropping systems is recognized as one of the best ways to enhance agricultural sustainability. While rotational benefits of forages have been established in small plot research trials, there is no documentation of whether these benefits are being observed on commercial farms, or whether producers manage forage stands to maximize rotational benefits. A survey of 253 Manitoba and Saskatchewan producers known to include forages in their crop rotations was conducted in 1992. The survey area was divided into six agroclimatic zones and correspondence analysis was used to test whether responses differed across the survey area. Sixty-seven percent of respondents indicated a yield benefit from including forages in the crop rotation, with the greatest yield benefit observed in wetter zones of the survey area. Eighty-three percent of the respondents observe weed control benefits for one (11% of respondents), two (50% of respondents), or more (33% of respondents) years after forages. The majority of respondents indicated that their forage acreage would not increase in the future. Average forage stand duration varied significantly (P < 0.10) with agroclimatic zone, ranging from 3 to 5 yr in wetter areas (south-central Manitoba) to 6 to 9 yr in the driest areas (south Saskatchewan). The two most common reasons cited for forage stand termination were reduced forage yield and damage by pocket gophers (presumably Thomomys talpoides and Geomys bursarius). Less than 12% of respondents cited rotational considerations as their primary reason for terminating forage stands, indicating that producers are not managing their forage crops to maximize rotational benefits. Producers relied heavily on tillage in both forage crop establishment and forage stand termination phases of the production system. It was suggested that decreasing the amount of tillage and fallow associated with forage-based cropping systems would not only facilitate increased cycling of forages in rotations, but also increase agricultural sustainability. Research Question Perennial forage crops are known to enhance sustainability of dryland cropping systems, hence, there is considerable interest in exploiting this traditional practice in modern agriculture. While there is considerable information on rotational benefits of forages from small plot research trials, there is no documentation of whether these rotational benefits are observed on commercial farms. Hence, the first objective was to determine whether producers perceive weed control and yield benefits from inclusion of perennial forages in their rotations, and to determine whether rotational benefits differ in the different agroclimatic zones of western Canada. The second objective was to determine whether producers' management practices are aimed at maximizing cycling of forage crops to capture rotational benefits, or whether they strive to maximize forage stand duration. Literature Summary There is a great deal of information about the benefits of including forage crops, especially forage legumes, in cropping systems. Forage crops improve soil quality and fertility, reduce soil erosion, suppress weeds, and help break plant disease cycles. In the Canadian prairie provinces, 15% of arable land (approximately 15 million acres) is seeded to introduced forage crops at any one time. An objective of extension workers is to cycle forages through the rotation effectively so that as many acres as possible can receive rotational benefits from forages in a shorter period of time. One Manitoba study showed that the economic optimum stand length of alfalfa was 4 to 5 yr, yet it is known that many of the rotational benefits can be achieved with 2 to 3 yr stands. Study Description A total of 253 Manitoba and Saskatchewan forage producers returned surveys in early 1992. The survey was designed to characterize the respondents' farm enterprise, with emphasis on forage crop production practices and the role of forages in the cropping system. Responses were divided into six unique agroclimatic zones based on established soil and climatic limitations. Applied Questions Do producers perceive yield and weed control benefits from including perennial forages in rotations? Sixty-seven percent of producers reported a yield boost from including forages in dryland crop rotations; however, the yield benefits were greatest in wetter areas. Eighty-three percent of respondents indicated fewer weeds for one (11% of respondents), 2 (50% of respondents), or more (33% of respondents) years. Many respondents indicated that fewer herbicides were required in grain crops seeded after forages compared with grain crops in an annual crop rotation. What is the average forage stand duration and why do producers terminate forage stands? The average forage stand duration was 6.5 yr; however, stand duration was shorter in wetter areas, and longer in drier areas. Almost 60% of respondents cited reduced forage yield as the major reason for terminating forage stands. Reduced yields were attributed to stand age, winterkill, and drought. Eighteen percent of respondents cited problems with pocket gophers as their primary reason for terminating forage stands. Only 11.6% of respondents cited rotational benefits as a primary reason for terminating forage stands. These observations suggest that the strategy of most producers is to maximize forage stand life, and rotate forages only when necessary due to declining productivity or weed invasion. What techniques do producers use to establish and terminate forage stands? Difficulties in foragestand establishment and termination are thought to be major obstacles to increased cycling of forages in crop rotations. Results of this study indicate that the most common seeding equipment was the press drill (50%) followed by the broadcast seeding method (20%), and airseederdhoe drills (20%). Use of hoe drills and airseeders may indicate some zero tillage forage establishment. Ninety percent of respondents reported using companion crops when establishing forages. Oat, wheat, and barley, which are known to be very competitive with forage seedlings, were the most commonly used companion crops. Flax, which is known to be less competitive with seedling forage plants, was used by fewer than 10% of producers, and was a favored companion crop in wetter areas. Tillage was the most common method of forage stand termination, although 22.1% of respondents use a combination of tillage and herbicides. Over 20% of producers indicate fallowing land for one full year after forage stand termination. Producers who used both tillage and herbicides relied less heavily on fallow the year after forage stand termination (19 vs. 27% for those who used tillage alone). It was concluded that opportunities for improving success of forage stand establishment and termination exist, and that these should be exploited to facilitate cycling of forages in crop rotations. Forage establishment could be enhanced by using soil-water-conserving seeding systems and less competitive companion crops. Reducing tillage prior to forage establishment should also reduce input costs (making shorter term rotations more economically attractive), and reduce soil erosion. Opportunities to enhance forage stand termination include reducing tillage intensity through substitution of herbicides for tillage, and reducing reliance on summerfallow the year after stand termination. Recommendations For rotational benefits of forage crops to be fully appreciated by producers, it would be useful to attach an economic value to the short- and long-term rotational benefits of forages. Therefore, additional studies on the short- and long-term economic benefits of forages in rotation are required. Such information would allow producers, extension agents, and crop consultants to deal more objectively with questions about forage stand duration, stand termination, rotation planning, etc. Research and demonstration work aimed at adapting reduced tillage forage establishment and stand termination systems to different forage producing regions (especially drier areas) are also required.
Год издания: 1995
Авторы: Martin H. Entz, W. John Bullied, F. Katepa‐Mupondwa
Издательство: Wiley
Источник: jpa
Ключевые слова: Ruminant Nutrition and Digestive Physiology, Soil Carbon and Nitrogen Dynamics, Bioenergy crop production and management
Открытый доступ: closed
Том: 8
Выпуск: 4
Страницы: 521–529