Yield, Nutritional Value, and Economic Benefits of Atriplex nummularia Lindl. Plantation in Marginal Dryland Areas for Conventional Forage Crops

• Published in: Arid land research and management 2005-10, Vol.19 (4), p.327-340
• Main Authors: Guevara, J.C, Allegretti, L.I, Paez, J.A, Estevez, O.R, Le Houérou, H.N, Silva Colomer, J.H
• Format: Article
• Language: English
• Subjects: alfalfa hay; Atriplex nummularia; browse biomass; crop yield; crude protein; dry matter accumulation; dryland farming; economic analysis; establishment cost; forage crops; grazing; maintenance cost; metabolizable energy; nutrient content; nutritive value; plant establishment; profitability; saline water; saltbush; seedlings; shrubs; total biomass; water table
• ISSN: 1532-4982; 1532-4990
• DOI: 10.1080/15324980500299672

This study assessed: (a) the total aerial and browse biomass of Atriplex nummularia Lindl. (saltbush) on ungrazed 9, 21, and 33-month old shrubs; (b) some relevant nutritional parameters for browse; and (c) the economics benefits of saltbush plantations in terms of cost ratios of energy and protein of saltbush vs. alfalfa, Medicago sativa L., hay. Three-month old nursery-grown speedlings were hand transplanted into a furrow bottom at a spacing of 1 × 2 m in an area with shallow (1-1.1 m deep) and moderately saline (4.6 dS m −1 ) water table. Seven rows of about 110 plants each were established. Linear regression equations of shrub volume on total and browse biomass were estimated. Nutritional parameters were determined for 33-month old shrubs. To estimate the cost of saltbush plantation, the following scenarios were considered: (a) poorly and adequately managed plantations (10- and 30-year life-span, respectively), (b) saltbush browse yields from 1.0 to 6.5 Mg DM ha −1 year −1 ,and (c) two management systems (cut-and-carry for pen feeding and direct browsing). For alfalfa crop, cultivated under irrigation, the life-span was four years and the yield was 10 Mg DM ha −1 year −1 from year two onward. Costs through the life-span of the two crops were discounted at present value using a 12.0% discount rate. Browse biomass was about 0.4, 0.8, and 1.4 kg DM shrub −1 for 9-, 21-, and 33-month old shrubs, respectively, or 6.5 Mg DM ha −1 year −1 for the oldest saltbush plants, corresponding with the surviving 4,665 shrubs ha −1 . Mean values of nutritional parameters were: organic matter, 74.7%; in vitro organic matter digestibility, 47.0%; ash, 25.3%; crude protein, 13.6%; Na, 5.6%; and Cl, 7.7%. Saltbush proved to be a highly productive species in areas that are marginal or unsuited for conventional crops such as alfalfa. The cost ratio saltbush/alfalfa hay for metabolizable energy and crude protein was lower than one for all the scenarios related to life-span and management systems of saltbush when saltbush yield was higher than 3.0 Mg DM ha −1 yr −1 . The overall mean cost ratio saltbush/alfalfa hay for crude protein and metabolizable energy for all the scenarios was 0.22, considerably lower than that considered in our hypothesis.