Chicory Roots out Nutrients in Soil.
Seasonal variability in high-quality herbage restricts optimal livestock production in the Appalachian region of the eastern United States.
Herbage deficits are caused by fluctuations in plant growth associated with seasonal cycles and short-term weather conditions -- especially drought in mid summer and cold in winter. But forage deficits can be overcome using combinations or sequences of plant resources that tolerate or can adapt to growing condition variations throughout the season. Often, these attributes are found in plants not typically considered forage resources.
An example is chicory, a perennial herb in the family Asteraceae that has a long history of production for chicons -- the edible, pale-leafed head used in salads. Documented chicory use in the United States can be traced to the late 1700s when the plant was introduced to the country as a coffee additive or substitute.
Chicory roots contain large quantities of inulin, a polysaccharide alternative to sucrose, which is low in calories but provides fiber and nutritional value. The root's high carbohydrate concentrations can be used for ethanol production using direct fermentation. When grown under optimal conditions, root dry mass ranges from 9 to 13 tons per acre (10 to 15 metric tons per hectare) with readily fermentable carbohydrate comprising up to half its mass.
The chicory root carbohydrates are used as herbal remedies in some Asian countries to produce hepato-protective pharmaceuticals. The plant was considered a noxious weed in the eastern United States until an improved cultivar called Grasslands Puna, developed in New Zealand for leafiness, was introduced as a forage resource in Pennsylvania in 1988.
The chicory plant is tap-rooted, similar to a carrot, and produces a rosette of basal leaves. It expresses a reproductive stem if the plant is allowed to grow undisturbed. Field-grown chicory has vegetative and reproductive components. The relative proportion of each is affected by canopy management so some plants remain vegetative while others differentiate and flower.
Chicory growth is highest during summer in the eastern United States, providing a resource that can improve available herbage in low-input grazing areas. Often, traditional grass and clover combinations on naturalized and managed pastures lag in summer growth due to heat and drought. But research in Britain shows that chicory persists when grown in shallow, drought-prone, chalky soils. It also provides herbage for livestock. Chicory's tap-root penetrates high bulk density subsoil, which may enable it to access water and nutrients deeper in soil. Climate and management influence chicory's persistence and productivity when grown for forage.
More research results
Studies in New Zealand and the United States show that chicory is better than grasses and clovers at absorbing mineral nutrients, such as potassium, calcium, magnesium, zinc and boron. Chicory could be used where confinement-fed livestock wastes are disposed of via land application. A manager's goals could focus on moving nutrients from the landscape and sequestering minerals in herbage to be harvested and removed from the site. One method could be to mix forages with different root architecture including tap-rooted plants such as chicory.
The most active roots on tap-rooted species are its youngest at the apex deep in soil. Grasses and clovers depend on roots originating at or near the soil surface.
An example of chicory's nutrient acquisition ability is illustrated by its soil phosphorus (P) concentrations measured over time. Research shows that three years after establishment, chicory plants grown in small plots have decreased in number ranging from less than 5 percent to 40 percent the plant of population. During that same period, soil P in the top 6-inch (15-centimeter) soil layer decreased 18 percent from 22 parts per million (milligrams per kilogram) the first year to 18 parts per million (milligrams per kilogram) by the third year. Soil P in the 6- to 12-inch (15-to 30-centimeter) layer decreased 67 percent from 12 parts per million (milligrams per kilogram) to 4 parts per million (milligram per kilogram). Chicory appeared to accelerate P depletion at the deeper soil layer.
Experiments using chicory as a component of swards from the outset of the experiment verified these results. Comparing the first and third production sequence years, soil P in the surface 6 inches (15 centimeters) decreased 33 percent under a stand of pure chicory, but 5 percent under a mixed stand of grass, birdsfoot trefoil and chicory. Soil P in the 6- to 12-inch (15- to 30-centimeter) soil layer decreased 46 percent under chicory and 22 percent under the mixture.
Concerns arise regarding use of nutrient-laden chicory herbage for animal feed as it can affect livestock health and increase metabolic disorders associated with mineral excess and imbalance. Elements such as copper and zinc, essential micro-nutrients for livestock health, accumulate in greater concentrations in chicory than grasses and legumes grown under the same conditions. But high copper concentrations might lead to imbalances with other essential nutrients such as molybdenum and sulfur. This problem can create livestock health concerns when chicory is a significant part of the diet.
While mineral content can be a positive attribute of chicory's nutritive value, the potential for nitrate- ([NO.sub.3]-) N or heavy metal ion accumulation can present health concerns where chicory forage is used for livestock production.
Chicory responds to nitrogen (N) in terms of dry matter accumulation. Stands of pure chicory produce up to 3 tons per acre (6.5 milligrams per hectare) with 430 pounds N per acre (480 kg N per hectare). The N content of chicory meets or exceeds that of common, high-quality forages such as alfalfa or well managed grass/legume mixtures. High N concentrations in herbage, and the linear increase in tissue N with increasing N inputs, suggest that forage chicory could be used to mop up N in soil.
Nitrates accumulate when N supply exceeds growth requirements, or when water deficit occurs. Chicory herbage reached [NO.sub.3]-N concentrations of more than 0.4 percent as the N rate increased from 107 to 214 pounds of N per acre (120 to 240 kilograms of N per hectare). Herbage nitrate concentrations greater than 0.4 percent present a potential health concern to livestock. N inputs on pure swards of chicory should be used with caution in livestock production situations. Nitrate accumulation could be minimized by splitting high N application rates across a season.
Chicory offers producers a means to improve seasonal distribution of available herbage in livestock production. The plant is compatible with commonly grown pasture plants in the Appalachian region and tolerates seasonal weather condition variations.
Mineral nutrient accumulation by chicory dictates a high level of input to sustain production, especially on soils with marginal fertility status. But the deep-rooted nature of the plant allows a producer to attenuate nutrient movement through the soil profile. Deep rooting is also beneficial to introduce organic matter, via senescing roots, deep in the soil profile, which affects soil quality.
Immediate benefits can be realized where management practices that incorporate chicory can minimize uncontrolled off-site nutrient movement.
David P. Belesky is a research agronomist and lead scientist with the hill-land grazing management project at USDA-ARS, Appalachian Farming Systems Research Center, 1224 Airport Road, Beaver, West Virginia 25813, USA; 304-256-2841, fax 304-256-2921, firstname.lastname@example.org.
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|Author:||Belesky, David P.|
|Publication:||Resource: Engineering & Technology for a Sustainable World|
|Article Type:||Brief Article|
|Date:||Feb 1, 2000|
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