Research Projects

Silvopastoral Research to Improve the Profitability of Beef Cattle Production, Ona, Florida

Project Team

• R. S. Kalmbacher, Principal Investigator, University of Florida, Ona, Florida

• M. Adjei, Asst. Professor, University of Florida, Ona, Florida

• Tom Anton, Asst. Professor, University of Florida, Ona, Florida

• Ikechukwu Ezenwa, Post-doc, University of Florida, Ona, Florida

Rationale/Objective

Silvopasture, combining the production of pines and beef on improved pastures, is one of the ways of diversifying and improving the profitability of cow-calf production in Florida. Identification of a reliable perennial forage legume that could make contributions to forage production and nutrition of grazing cattle in the late summer and early fall would also significantly improve profitability of the industry. Leucaena spp., a tropical forage tree legume, has shown potential in clipping and grazing studies. In our previous studies, we developed a system that utilized 3-month old seedlings to achieve >80% establishment success of leucaena. However, establishment success and use is also hampered by soil acidity and limited root growth on acid, infertile Spodosols of south Florida. The objectives of these studies are to obtain information on pine, forage, and cattle productivity in silvopasture, evaluate selected leucaena germplasm for adaptability to south Florida, determine the potential of leucaena agroforestry for goat production, and address the main factors involved in leucaena establishment failures with a view to improving reliability of field establishment.

Work done

Experiment 1: Forage and cow-calf production in south Florida slash pine-bahiagrass silvopasture

Forage yields and cow-calf production under south Florida slash pine-bahiagrass silvopasture at the UF/IFAS Range Cattle Research and Educational center, Ona, FL were determined. The pines were planted in 1991 at 1120 trees ha^-1 in a 1.2 x 2.4 x 12.2 m double-row configuration. The 15-ha pasture was fertilized once in February 2003 with 336 kg/ha of 16-4-16 N:P:K fertilizer + micronutrients, providing 54 kg N ha^-1. Using exclusion cages, forage production at the center of the alleys, near the tree rows and between the tree rows were determined by sampling every 42 d from April to September. Available forage was measured on 28-d intervals by sampling 7.3-m strips. To quantify cow-calf production, the silvopasture was divided into two 7.5-ha blocks. In one block, the tree density remained at 500 trees ha^-1 while in the second block tree density was thinned to 300 trees ha^-1. Silvopasture was compared with an 8-ha open pasture. Braford cows (52 cows weighing an average of 510 kg at start) and calves (112 d-old, 164 kg at start) were stocked at ~2 cow-calf pairs/ha from 1 June to 15 Sept. 2003 (weaning). In March and April, 2003, soil samples were collected in 71 profiles: 20 profiles each in thinned and not thinned slash pine-bahiagrass silvopasture, 20 in a slash pine-native silvopasture, and 11 in an open bahiagrass pasture. Soil will be analyzed for pH, total C, N, NO₃-N, NH₄-N, Mehlich-1 P, soluble reactive PO₄, Al, Ca, and Mg.

Biomass and edible forage DM yields and chemical composition of 10 leucaena selections were measured at Ona, Ft. Pierce, and Brooksville from April through December, 2003. Trees were cut when their regrowth on 0.5-m tall stubble reached 1.5-2.0-m height. The sites represent different soil, drainage, and climatic conditions representative of three regions in Florida. The plots were established in July 2002 by transplanting 8-week old plants into two 6-m long rows spaced 1 m apart with 25 cm within row spacing. Data was taken from the inner 2-m segment of each double-row plot.

During July to November 2003, we grazed 45 newly-weaned three-quarter Boer x Spanish wethers and does (average weight 17 kg at start) in bahiagrass with or without protein (soybean) supplementation or bahiagrass + leucaena (K636) pasture. In the bahiagrass + leucaena pastures, leucaena was planted in three rows (rows 1 m apart between and within rows) with a 5-m alley of bahiagrass between the triple-rows. Goats were stocked at 27 goats/ha in all pastures, and all treatment groups received one-third of their daily energy requirement through a mixed ration of cracked corn and soybean hulls, with molasses to reduce dustiness. Protein-supplemented goats received, in addition, soybean meal to supply half of their daily protein requirement (50% protein).

The rooting depth of leucaena and influence of soil amendment were studied on a native Myakka fine sand soil. In a 9 x 9 m area, points were randomly selected in a 1.2 x 1.2 m grid pattern. From each point, the A (33 cm from the surface), E (next 34-66 cm), and Bh (up to 100 cm depth) horizons were excavated using a post-hole digger that made 15-cm diameter holes. Dolomite was mixed with each horizon according to treatment, and the soil returned to the hole. Fertilizer (0-10-20 with micronutrients) was mixed into each A-horizon soil at 560 kg/ha. The treatments were: A horizon mixed with or without dolomite (L-A, NL-A); A and E horizons mixed with or without dolomite (L-E, NL-E); A, E, and Bh horizons mixed with or without dolomite (L-Bh, NL-Bh), and a control - A, E, and Bh horizons mixed with dolomite. Dolomite was applied at 4.5 Mg/ha. In every hole, except the control, 5 g of strontium was deposited at the lowest excavated depths of the profiles using a 1-m long 8-cm diameter PVC pipe before the excavated horizon(s) were returned into the holes. The soils were returned in reverse order (Bh first, then E, and A in that order), with some compaction. Three month-old leucaena seedlings, averaging 30 cm in height, were transplanted into each profile on 30 May 2003.

Results

Experiment 1: Forage and cow-calf production in south Florida slash pine-bahiagrass silvopasture

Significantly higher grass yield was obtained from the center of the alleys (10.5 Mg DM ha^-1) than from adjacent to and between tree rows with 7.7 and 3.1 Mg DM ha^-1, respectively. Annual forage production was higher in open pasture (10.2 Mg DM/ha) than in the silvopastures, which were not different and averaged 7.5 Mg DM/ha. Available forage averaged 2.5 Mg DM/ha at the start in June. Available forage increased on open pasture for the first 56 d, then declined. Available forage declined from June to September on both silvopastures. Cows lost an average of 88.1 kg on silvopastures compared with a loss of 21.7 kg for open pasture. At weaning (age 236 d), calves on open pasture (211.6 kg) were heavier than those on the silvopastures (138.0 kg), which were not different.

After four harvests in 2003, the following selections had total biomass (leaf + stem) DM yields of >5 Mg/ha at Ona: K636, K156, KX2, L. diversifolia, COSAF, and K784, with 5.4 to 8.6 Mg/ha). These selections also had the highest leaf DM yields of 2.9 to 4.4 Mg/ha. Dry matter yields were higher in Ft. Pierce where biomass and leaf DM yields were 12.3 to 20.1 and 5.7 to 9.8 Mg/ha, respectively. Selections K636, KX2, and LxL were the highest yielding selections at Ft. Pierce. At both Ona and Ft. Pierce, there were no differences for crude protein concentrations in leaves, which averaged 26% at each location. For in vitro organic matter digestibility (IVOMD), K636 (52%) and K340 (59%) were the only selections with IVOMD >50%. At Ft. Pierce, the three highest-yielding selections, K636, KX2, and LxL, had 58 to 60% IVOMD, and K340, K156, and L. macrophylla also had IVOMD >50%. Data from Brooksville are not yet available.

Experiment 3: Performance of goats grazing leucaena-bahiagrass pastures.

Available bahiagrass averaged 5 Mg DM/ha in the 50% protein and control pastures and 3.6 Mg DM/ha in the bahiagrass + leucaena pastures. Leaves available from the leucaena varied between 101 kg DM/ha/month in July to 24 kg DM/ha/month in October. At the stocking rate used, grass was not limiting throughout the grazing period, and goats in the bahiagrass + leucaena pastures had access to enough leaves to provide supplementary grazing. In five months, July to November, goats on leucaena + bahiagrass gained 8.6 kg compared with an average of 4.1 kg on 50% protein and control treatments, respectively.

Data on shoot growth will be recorded this summer. Strontium concentrations in leucaena leaves sampled every 3 months beginning in May, 2004, will be analyzed, and Sr uptake will be used as an index of root proliferation down the profile.

Planned for 2004

Second-year data will be collected in the following experiments: (1) Forage and cow-calf production in thinned, not-thinned silvopasture, and open pasture; (2) Evaluation of leucaena selections; and (3) Performance of goats grazing leucaena-bahiagrass pastures. Soils taken from 1-m deep profiles in the thinned and not-thinned silvopastures, and open pasture will be analyzed and used to describe nutrient status and cycling in the systems (See Nair et al.). Data on shoot growth and uptake of Sr of leucaena plants in the field profile modification trial will be measured to validate earlier greenhouse research.

Publications/Output (2002 to date)

Refereed journals

Ezenwa, I.V., R.S. Kalmbacher, and F.G. Martin. 2004. Profile modification with dolomite and surface-incorporated dolomite-gypsum mixtures and early leucaena growth. Communications in Plant Science and Soil Analyses (in review).

Ezenwa, I.V. and R.S. Kalmbacher. 200_. Emergence and survival of leucaena on poorly drained soil and management practices to mitigate negative effects. Tropical Grasslands (in review).

Ezenwa, I.V., R.S. Kalmbacher, and F.G. Martin 200_. Effects of surface and subsoil incorporation of dolomite and dolomite-gypsum mixtures on leucaena seedling growth. Communications in Soil Science and Plant Analysis (in review).

Ezenwa, I., M.E. Bannister, J. Nowak, and R.S. Kalmbacher. 2002. History and potential of silvopasture in Southeastern U.S. Annual Meeting Abstracts, CD-ROM. American Society of Agronomy, Madison, WI.

Ezenwa, I. and R.S. Kalmbacher. 2003. Overcoming main constraints of leucaena establishment on Spodosols in south Florida. Annual Meeting Abstracts, CD-ROM. American Society of Agronomy, Madison, WI.

Ezenwa, I.V., R.S. Kalmbacher, and F.G. Martin. 2003. Summer forage yield of a slash pine-bahiagrass silvopasture in south-central Florida. Southern Branch of the American Society of Agronomy Annual Meeting, February 2-4, 2003, Mobile, AL, p14.

Nair, V.D. and R.S. Kalmbacher. 2004. Silvopastures as an approach to reducing nutrient loading of surface water from farms. p.141. In Book of Abstracts. Mosquera-Losada et al. (ed.) Silvopasturalism and Sustainable Management International Congress, Lugs, Spain. Crop Prod. Dep. High Politechnic School, Universidad Santiago de Compostela, Unicopia, Lugo.

Ezenwa, I.V., R.S. Kalmbacher, and W.J. Mallett. 2003. Projected yields of south Florida slash pine silvopasture in south central Florida. Soil Crop Sci. Soc. Fla. Proc. 62: 47-50.

Kalmbacher, R.S., I.V. Ezenwa, and Butch Mallett. 2002. Pine production from silvopasture in south Florida. The Florida Cattleman and Livestock Journal (September 2000), p.64.

Kalmbacher, R.S. and I.V. Ezenwa. 2003. Forage and cattle production in slash pine-bahiagrass silvopasture at Ona. Range Cattle Research and Education Center Newsletter, December 2003, Vol. 6 No. 4, p.2.

Ezenwa, I. 2003. Growing leucaena in south Florida. Range Cattle Research and Education Center Newsletter, June 2003, Vol. 6 No. 2, pp.4-5.

Ezenwa, I. and R.Kalmbacher. 2003. Forage production from silvopastures in south Florida. Range Cattle Research and Education Center Newsletter, March 2003, Vol. 6 No. 1, pp.4-6.

Kalmbacher, R. and I. Ezenwa. 2003. Forage and cattle production from in slash pine bahiagrass silvopastures at Ona. Range Cattle Research and Education Center Newsletter, March 2003, Vol. 6 No. 4, p.2.

Ezenwa, I.V., R.S. Kalmbacher, M.J. Williams, L.A. Gary, and J.D. Arthington. 2004. Liveweight gain of meat goats grazing leucaena-bahiagrass pasture. Range Cattle Research and Education Center Newsletter, March 2003, Vol. 7 No.1, pp.5-6.

Ezenwa, I. 2003. Agroforestry systems for sustainable beef production in south Florida. Range Cattle Research and Education Center Field Day, May 15, 2003. Range Cattle REC, Ona Research Report RC-2003-2, pp. 17-21.

Ezenwa, I.V., R.S. Kalmbacher, M.J. Williams, L.A. Gary, and J.D. Arthington. 2004. Leucaena Provides a High-Protein Grazing for Goats, Part 1. Caprine Chronicle 19 (2): 14.

Ezenwa, I.V., R.S. Kalmbacher, M.J. Williams, L.A. Gary, and J.D. Arthington. 2004. Leucaena Provides a High-Protein Grazing for Goats, Part 2. Caprine Chronicle 19 (3).

Kalmbacher, R.S. 2002. Management of cattle: Utilizing silvopasture. In: J. Nowak (editor) Silvopastoral Systems in North Florida – Design, Implementation and Benefits, In-Service Training for County Agents, Marianna, Florida, April 2002. Univ. of Florida Agricultural Extension Service.

Ezenwa, I. and R. Kalmbacher. 2003. Silvopastoral systems: Managing forage, livestock and timber for higher returns. Forage Workers’ Tour, Okeechobee, FL July 10-11, 2003.

Ezenwa, I.V., R.S. Kalmbacher, M.J. Williams, D.O. Chellemi, and F.G. Martin. 2003. Evaluating leucaena in three Florida environments. Annual Meeting of the Soil and Crop Science Society of Florida, 19-21 May, 2003, Daytona Beach, FL.

Ezenwa, I. 2004. Grazing goats on leucaena. Florida Meat Goat Association Central Florida Chapter Meeting, Kevuda Haven Cabrito Farm, Center Hill, FL, November 2003.

Ezenwa, I.V. and R.S. Kalmbacher. 2004. Forage production and cattle production on slash pine-bahiagrass silvopasture in south Florida. First World Congress of Agroforestry. 27 June – 2 July, 2004. Orland FL. Center for Subtropical Agroforestry, University of Florida, Gainesville.

Nair, V.S., S. Allen, D. Graetz, R.S. Kalmbacher, and I.V. Ezenwa. 2004. Phosphorus and nitrogen dynamics in silvopasture, open pasture, and rangeland in south-central Florida. In: First World Congress of Agroforestry. 27 June – 2 July, 2004. Orland FL. Center for Subtropical Agroforestry, University of Florida, Gainesville.

Ezenwa, I.V., R.S., Kalmbacher, M.J. Williams, L.A. Gary, and J.D. Arthington. 2004. Liveweight gains on Boer x Spanish goats grazing leucaena + bahiagrass in south Florida. 2004 Meeting of the Southern Branch of the American Society of Agronomy, June 27-29, 2004, Biloxi, Mississippi.

Ezenwa, I.V., R.S., Kalmbacher, M.J. Williams, L.A. Gary, and J.D. Arthington. 2004. Performance of Boer goats grazing leucaena and bahiagrass with or without supplementation. Meeting of the Soil and Crop Science Society of Florida, May 19-21, 2004, Tallahassee, FL.

Kalmbacher, R.S. and I. Ezenwa. 2004. Forage and livestock production in a 12-yr silvopasture. 2004 Annual Meeting of the Soil and Crop Science Society of Florida, 19-21 May, 2004, Tallahassee, FL.

Drs. Kalmbacher, Bannister, and Nair (L to R) discuss the silvopasture trial installed at Ona, Florida