**5. Rotations for forage crops**

Prior to the extensive production of soybean for seed in the United States, and important rotation scheme in much of the New England, Mid-Atlantic and North Central states was corn-winter wheat-red clover. Frequently the red clover would be over seeded in late winter or early spring in the developing wheat crop. Many times timothy (*Phleum pretense* L.) a cool-season perennial grass would be seeded along with the red clover. The mixture

Soil tests are usually acquired prior to seeding to determine nutrient availability. Applications of pulverized limestone are often required to supply Ca and adjust pH levels to facilitate establishment of a forage legume. Many soils in temperate climates tend to be acidic (pH 4.5 to 5.5) and require liming to elevate soil pH levels to 5.7 or higher to be more suitable for legume establishment. Virtually all recommendations for pasture renovation in temperate climates call for the establishment of one or two legumes in the sward (Wheaton and Roberts, 1993; Johnson et al., 2007; Lacefield and Smith, 2009; Teusch and Fike, 2009). Wheaton and Roberts (1993) listed 10 benefits of including a forage legume in a pasture mix. Among them were an increase in animal gain, decrease in herd health problems, an increased conception rate by cows, an increased protein yield per hectare, N being furnished by the legume to the grass, and reduced pasture production costs. Johnson et al., (2007) stated some of the same benefits along with a better seasonal distribution of forage because legumes are generally more productive in mid-summer than cool-season grasses which are the more common grass types grown in temperate climates. Lacefield and Smith (2009), reported that tall fescue (*Festuca arundinacea* Schreb.) growing in conjunction with red clover seeded at 6.7 kg ha-1 yielded more dry matter (12,400 kg ha-1) than fescue alone fertilized with 202 kg N ha-1 (11,100 kg ha-1). Teusch and Fike (2009) list several legume species to be considered for seeding in pasture renovation. The more common legume species recommended are red clover, ladino clover (*Trifolum repens* L.), annual lespedeza (*Lespedeza striata* Maxim.), alfalfa, and birdsfoot trefoil (*Lotus corniculatus* Cav.). As stated previously, in temperate climates cool season grass species are frequently selected to be seeded along with the legume when renovating pastures. For permanent pastures the species of choice are often tall fescue, orchard grass (*Dactylis glomerata* L.), or smooth brome (*Bromus inermis*  L.). Pasture management is an on-going operation and additional seedings may be necessary to maintain a profitable sward. Birdsfoot trefoil has the ability to reseed itself even under grazing and alfalfa is a long-lived legume with individual plants able to survive up to five years. Red clover, though a perennial, will usually last only about three years and will need to be reseeded. Some forage specialists have found that over-seeding the pasture annually with 4.5 kg ha-1 of red clover seed in mid-winter will maintain the sward at about 30% legume which is recommended as the proper mix of grass and legume (H.N. Wheaton, 1975, personal communication). Even with good management, most pastures will need

renovation about ever four to five years due to weed growth.

Pasture renovation in sub-tropical climates usually involves complete destruction of the old sward and reseeding or sprigging to reestablish the grass. The reasons or renovation in the sub-tropics are usually for weed control, or to reestablish swards lost to insects, over grazing, prolonged drought and in some cases multiple freezes during late winter that kill off the grasses. Renovation may also be done to replace an older grass cultivar with a newer more productive one (Woodruff et al., 2010). One basic difference between temperate pasture renovation and sub-tropical pastures is that in the sub-tropics the old sward is essentially destroyed and a new one established (Verdramini et al., 2010). Sub-tropical pastures are not as apt to include a forage legume due to most of those species being coolseason and may not survive well in hot humid summer months. Also, many of the grass species used are aggressive in nature and effective at crowding out less aggressive species. The more common species grown as pasture grasses in the subtropics are hybrid bermudagrass (*Cynodon dactylon* (L.) Pers.), bahiagrass (*Paspalum notatum*), atra paspalum (*Paspalum atratum* Swallen), digitgrass (*Digitaria decumbens*) (En), limpograss (*Hemarthria* 

would provide some pasture or hay the first year after the wheat was harvested but was most productive the following year. The two species combined will provide more forage production together than each species separately (Martin and Leonard, 1967). These fields would frequently then be plowed in fall or spring of the second year with the sward providing a green manure crop for the following season. Sometimes only red clover would be over seeded in the wheat solely for the purpose of being used as a green manure crop. Other grass species would occasionally be seeded with the red clover and sometimes the field would remain in red clover-grass for two or more years to provide hay and grazing. Though this rotation is comparatively old, it is still practiced, especially where there are numerous beef cow-calf, dairy, or horse enterprises.

Both beef and dairy cattle farming involves crop management challenges that many tend to overlook when thinking about crop rotations. Many people do not think of pasture swards as being a "crop". But to the cattleman it is a very important source of income and deserves as much attention to management as any other economic plant life. Dairy farms are very dependent on careful management of feed and forage resources in order to be sustainable. Not only is the quantity of feed and forage important to the dairy animal but quality as well, to insure maximum milk production during lactation. Roth et al., (1997), list a number of suggestions to aid dairy farmers in developing long term crop rotation plans that address production issues, such as feed quantities, forage quality, fertility, and pest control issues as it relates to corn silage production. Greater restrictions on pesticide use, are often placed on dairy operations due to concerns over traces of some chemicals carrying over into milk that is consumed by children. Continuous corn silage production carries the risk of corn rootworm damage, and as pointed out earlier, the western corn rootworm has adapted to egg laying in soybean fields and can damage corn following soybean. Roth (1996) points out that western corn rootworm larvae cannot tolerate a rotation to alfalfa. Therefore, seeding alfalfa after corn for silage will not only provide a good source of quality hay but also eliminate the need for a soil insecticide for rootworm control in the following corn crop.

Temporary meadows, which are seeded into a forage species for one to three years and then cultivated for a grain crop are sometimes included in discussions regarding crop rotations. However, a number of dairy farms and beef cow-calf operations occur in areas that include land unsuitable for tillage of any kind and are often used as permanent pastures that should be managed with the same intensity as any other cropland. Without proper attention these areas will often revert to a high proportion of weedy or woody species that are not useable by livestock and low yielding forage that reduces the pasture's carrying capacity or places greater demands on tillable cropland to provide necessary feed to maintain the animal enterprise. Johnson et al., (2007) states that periodic renovation or "renewing" of a pasture is the best way to improve forage yield and animal performance. Pasture renovation is in a way a form of crop rotation if you consider crop rotation as a means of maintaining land productivity. In temperate climates renovation usually begins in the fall by overgrazing the pasture to be renovated to remove excess vegetative material that might interfere with seeding and germination of the new pasture mix ( Johnson et al., 2007; Lacefield and Smith, 2009). Seeding usually occurs in mid-winter while the soil is frozen in the first few centimeters. The thawing and refreezing of the soil surface is usually sufficient to allow good contact of the forage seed with the soil for germination. Sometimes a light cultivation with a disk or spike-toothed harrow is done to improve the chances of a good soil-seed contact.

would provide some pasture or hay the first year after the wheat was harvested but was most productive the following year. The two species combined will provide more forage production together than each species separately (Martin and Leonard, 1967). These fields would frequently then be plowed in fall or spring of the second year with the sward providing a green manure crop for the following season. Sometimes only red clover would be over seeded in the wheat solely for the purpose of being used as a green manure crop. Other grass species would occasionally be seeded with the red clover and sometimes the field would remain in red clover-grass for two or more years to provide hay and grazing. Though this rotation is comparatively old, it is still practiced, especially where there are

Both beef and dairy cattle farming involves crop management challenges that many tend to overlook when thinking about crop rotations. Many people do not think of pasture swards as being a "crop". But to the cattleman it is a very important source of income and deserves as much attention to management as any other economic plant life. Dairy farms are very dependent on careful management of feed and forage resources in order to be sustainable. Not only is the quantity of feed and forage important to the dairy animal but quality as well, to insure maximum milk production during lactation. Roth et al., (1997), list a number of suggestions to aid dairy farmers in developing long term crop rotation plans that address production issues, such as feed quantities, forage quality, fertility, and pest control issues as it relates to corn silage production. Greater restrictions on pesticide use, are often placed on dairy operations due to concerns over traces of some chemicals carrying over into milk that is consumed by children. Continuous corn silage production carries the risk of corn rootworm damage, and as pointed out earlier, the western corn rootworm has adapted to egg laying in soybean fields and can damage corn following soybean. Roth (1996) points out that western corn rootworm larvae cannot tolerate a rotation to alfalfa. Therefore, seeding alfalfa after corn for silage will not only provide a good source of quality hay but also eliminate the need for a soil insecticide for rootworm control in the following corn crop. Temporary meadows, which are seeded into a forage species for one to three years and then cultivated for a grain crop are sometimes included in discussions regarding crop rotations. However, a number of dairy farms and beef cow-calf operations occur in areas that include land unsuitable for tillage of any kind and are often used as permanent pastures that should be managed with the same intensity as any other cropland. Without proper attention these areas will often revert to a high proportion of weedy or woody species that are not useable by livestock and low yielding forage that reduces the pasture's carrying capacity or places greater demands on tillable cropland to provide necessary feed to maintain the animal enterprise. Johnson et al., (2007) states that periodic renovation or "renewing" of a pasture is the best way to improve forage yield and animal performance. Pasture renovation is in a way a form of crop rotation if you consider crop rotation as a means of maintaining land productivity. In temperate climates renovation usually begins in the fall by overgrazing the pasture to be renovated to remove excess vegetative material that might interfere with seeding and germination of the new pasture mix ( Johnson et al., 2007; Lacefield and Smith, 2009). Seeding usually occurs in mid-winter while the soil is frozen in the first few centimeters. The thawing and refreezing of the soil surface is usually sufficient to allow good contact of the forage seed with the soil for germination. Sometimes a light cultivation with a disk or spike-toothed

numerous beef cow-calf, dairy, or horse enterprises.

harrow is done to improve the chances of a good soil-seed contact.

Soil tests are usually acquired prior to seeding to determine nutrient availability. Applications of pulverized limestone are often required to supply Ca and adjust pH levels to facilitate establishment of a forage legume. Many soils in temperate climates tend to be acidic (pH 4.5 to 5.5) and require liming to elevate soil pH levels to 5.7 or higher to be more suitable for legume establishment. Virtually all recommendations for pasture renovation in temperate climates call for the establishment of one or two legumes in the sward (Wheaton and Roberts, 1993; Johnson et al., 2007; Lacefield and Smith, 2009; Teusch and Fike, 2009). Wheaton and Roberts (1993) listed 10 benefits of including a forage legume in a pasture mix. Among them were an increase in animal gain, decrease in herd health problems, an increased conception rate by cows, an increased protein yield per hectare, N being furnished by the legume to the grass, and reduced pasture production costs. Johnson et al., (2007) stated some of the same benefits along with a better seasonal distribution of forage because legumes are generally more productive in mid-summer than cool-season grasses which are the more common grass types grown in temperate climates. Lacefield and Smith (2009), reported that tall fescue (*Festuca arundinacea* Schreb.) growing in conjunction with red clover seeded at 6.7 kg ha-1 yielded more dry matter (12,400 kg ha-1) than fescue alone fertilized with 202 kg N ha-1 (11,100 kg ha-1). Teusch and Fike (2009) list several legume species to be considered for seeding in pasture renovation. The more common legume species recommended are red clover, ladino clover (*Trifolum repens* L.), annual lespedeza (*Lespedeza striata* Maxim.), alfalfa, and birdsfoot trefoil (*Lotus corniculatus* Cav.). As stated previously, in temperate climates cool season grass species are frequently selected to be seeded along with the legume when renovating pastures. For permanent pastures the species of choice are often tall fescue, orchard grass (*Dactylis glomerata* L.), or smooth brome (*Bromus inermis*  L.). Pasture management is an on-going operation and additional seedings may be necessary to maintain a profitable sward. Birdsfoot trefoil has the ability to reseed itself even under grazing and alfalfa is a long-lived legume with individual plants able to survive up to five years. Red clover, though a perennial, will usually last only about three years and will need to be reseeded. Some forage specialists have found that over-seeding the pasture annually with 4.5 kg ha-1 of red clover seed in mid-winter will maintain the sward at about 30% legume which is recommended as the proper mix of grass and legume (H.N. Wheaton, 1975, personal communication). Even with good management, most pastures will need renovation about ever four to five years due to weed growth.

Pasture renovation in sub-tropical climates usually involves complete destruction of the old sward and reseeding or sprigging to reestablish the grass. The reasons or renovation in the sub-tropics are usually for weed control, or to reestablish swards lost to insects, over grazing, prolonged drought and in some cases multiple freezes during late winter that kill off the grasses. Renovation may also be done to replace an older grass cultivar with a newer more productive one (Woodruff et al., 2010). One basic difference between temperate pasture renovation and sub-tropical pastures is that in the sub-tropics the old sward is essentially destroyed and a new one established (Verdramini et al., 2010). Sub-tropical pastures are not as apt to include a forage legume due to most of those species being coolseason and may not survive well in hot humid summer months. Also, many of the grass species used are aggressive in nature and effective at crowding out less aggressive species. The more common species grown as pasture grasses in the subtropics are hybrid bermudagrass (*Cynodon dactylon* (L.) Pers.), bahiagrass (*Paspalum notatum*), atra paspalum (*Paspalum atratum* Swallen), digitgrass (*Digitaria decumbens*) (En), limpograss (*Hemarthria* 

reported that winter wheat yields in the central Great Plains were negatively affected by eliminating the 11 to 14 month summer fallow by spring planting a transitional crop before wheat in the fall. However, a spring planted forage crop that was harvested early had a minimum negative impact on wheat yields and that the value of the forage combined with the following wheat yields resulted in greater income than the traditional winter wheatfallow rotation. Research from the Horse Heaven Hills region of Washington looked at a continuous no-till hard red spring wheat system verses a winter wheat-fallow rotation and found the hard red spring no-till system did not match the winter wheat-fallow system of production in yield or income. However, the continuous no-till system did offer a benefit of providing ground cover that reduced wind erosion and air pollution by dust particles

Summer fallow is also practiced on fields used to produce castor bean (*Ricinus communis* L.) the previous year. This is not done for accumulating moisture but to rid the field of any volunteer plants. Castor bean contains a very deadly toxin, ricin, which in very small quantities can kill humans and livestock. Summer fallow in this case allows volunteer

Organic farming has embraced crop rotations as its backbone to success. Crop rotation is practiced with what appears to be, much more intensity than most conventional farming systems with particular emphasis on sustainability. A crop rotation plan and accompanying records for a field and/or farm are required for certification as an organic farming operation (Johnson and Toensmeier, 2009). Organic farming and its use of crop rotations could be summed up in part, as the employment of proven crop management practices prior to the advent of pesticides and processed fertilizers. This is not to say that improvements on those rotation systems have not occurred. Most have been modified to accommodate mechanization and most other time saving ideas. But, yields may be lower. Maeder et al., (2002) reported on a 21 year study in Europe that crop yields on organic farms were generally 20% lower. However, there was an offsetting decrease of 34% in fertilizer expense, a 53% reduction in energy costs, and a 97% decrease in pesticides. Reganold et al., (1987) reported a comparison of the long-term effects (40 years) of conventional farming to organic systems found that organic farms had significantly higher levels of soil organic matter than conventional systems, greater top soil depth, higher polysaccharide content, and less soil erosion. Clark et al., (1998) reported that over an eight year period of applying organic crop rotation practices that soil organic matter had increased 2% over a comparable field that

A major challenge to organic crop production is control of weeds. Weed management has been identified by producers as the principle problem in organic farming (Walz, 1999). The advent and subsequent extensive use of herbicides after World War II altered crop production practices, especially crop rotations. Conventional crop farming today usually involves two- or three-crop crop rotations as have been previously mentioned with a heavy reliance on herbicides to at least reduce or eliminate weed problems. Regardless of the type of farming system used, conventional or organic, weeds are a constant annual drag on achieving maximum yields of high quality produce. Nave and Wax (1971) reported a reduction in soybean seed yields of between 25% to 30% compared to weed free plots due to

plants to be destroyed and the field cleaned for future feed and food crops.

**7. Organic farming and crop rotations** 

used conventional practices in a two-year rotation scheme.

(Young et al., 2000).

*altissima*), and Rhodes grass (*Chloris gayana (Kunth)*) (Verdramini et al., 2010). All of these grasses except atra paspalum, bahiagrass and Rhodes grass require vegetative propagation in order to be established. As with temperate pastures, the pasture must first be properly prepared by controlling weeds, insects, removing old or dead vegetative material and fertilizing to soil test recommendations. Burning is often used in preparing bermudagrass pastures for renovation (Stichler and Bade, 2005). Tillage operations are often performed during dry periods in the spring to further control weeds and old sward growth as well as better prepare the land for vegetative propagation with the onset of summer rains (Stichler and Bade, 2005;Verdramini et al., 2010). In both the subtropical and temperate climates warm season annual forages may be included into crop rotations on land used primarily for cultivated crops. This is to provide additional pasture, hay or silage for livestock operations. Species such as pearl millet (*Pennisetum glaucum (L.) R.Br.),* sudangrass *(Sorghum bicolor* subsp. *Drummondii* (Steud.) de Wet ex Davidse), and other forage sorghum and sorghum x sudangrass crosses often fill this role (Hancock, 2009).
