Coating nursery containers with copper carbonate improves root morphology of five native Australian tree species used in agroforestry systems

Seedlings of the native Australian tree species Acacia holosericea, Casuarina cunninghamiana, Eucalyptus argophloia, E. camaldulensis and Melaleuca bracteata, were raised in nursery containers which were coated with CuCO₃ (50 g l^-1, in a water-based paint solution) or left uncoated for three months. Seedling growth of all species in the nursery was generally less in treated containers, although differences were relatively small. More importantly, CuCO₃ treatment reduced the occurrence of lateral roots growing down or coiling around container walls for both three- and six-month-old seedlings. Twenty-four months after planting both three- and six-month-old seedlings on a semiarid site in subtropical southeast Queensland, there was no effect of CuCO₃ treatment on height or basal diameter development of seedlings. However, sample excavations of root systems showed that the poor root morphology exhibited by untreated seedlings when in the nursery had persisted in the field. As such poor root form has the potential to reduce tree growth and wind firmness in the longer term, these results suggest that chemical root-pruning is a helpful nursery practice when raising seedlings for dryland afforestation, and in circumstances where it may be necessary to retain seedlings in the nursery for longer than normal to take advantage of infrequent rainfall events. This revised version was published online in June 2006 with corrections to the Cover Date.     

Combination of cacao with other plantation crops: an agroforestry system in Southeast Bahia,Brazil

Brazil accounts for about 20% of the world production of cocoa, and about 95% of cocoa produced in Brazil is from the southeastern part of Bahia State. Traditionally, cacao is grown in monoculture (though under the shade of various other species). But various crop combinations involving cacao have recently been undertaken by the farmers with encouragement from Brazilian government.As a part of the crop diversification programme in the traditional cacao growing areas and their surroundings, extensive areas are being planted to other plantation crops, mainly clove and rubber and, to some extent, coconut too. Crop combinations have been adopted in some of these new plantings and cacao is an important component of most of such combinations. Whereas several other crops are combined with clove trees, cacao is usually the only species grown with mature rubber trees. Young rubber trees are, however, interplanted with a number of other species. Productive coconut areas are found mostly in sandy soils along the coast so that there is little intercropping. However, scattered farms are found where coconuts are underplanted with guarana, black pepper, cacao, cashew, etc. as done commonly in other parts of Northeast Brazil.     

Paraiso (Melia azedarach var. “Gigante”) woodlots: an agroforestry alternative for the small farmer in Paraguay

This paper describes the salient aspects and analyses the potential of the Paraiso Woodlot System, which is becoming popular as an agroforestry alternative to land use in the degraded acid sandy soils of the humid sub-tropical Guayaybi area of Paraguay. The system consists of a combination of paraiso (Melia azedarach var gigante) with other trees, especially Leucaena leucocephala, and annual crops.The fast growth habit, deep root system, addition of large quantities of organic matter through leaf and litter fall, compatibility with agricultural crops, high value of the sawlogs and production of substantial quantities of poles and firewood make paraiso an excellent species for agroforestry combination. Preliminary results of the trials indicate that the woodlots are successful and with increasing efforts of the extension agencies, they are being accepted as a viable alternative to traditional agricultural systems.Besides discussing the potential of these woodlots based on initial results, the paper identifies the constraints of the system and highlights the priority research areas.     

Integration of pines and pastures for hay and grazing

When combining pine and cattle production on improved pastures, grazing may have to be delayed for several years until trees are large enough to resist injury. During this period forage would be lost unless harvested for hay. This study in south Georgia, USA, examined hay production during the first 3 years, cattle production during the next 3 years, and effects of this management system on survival and growth of slash pine(Pinus elliottii) planted in widely-spaced rows within the pastures. Pines were planted at 225 trees/ha in configurations of 3.0 x 14.6 or 4.9 x 9.1 m in pastures recently sprigged or seeded with Coastal bermudagrass (Cynodon dactylon) or Pensacola bahiagrass(Paspalum notatum). Pastures were fertilized annually and cut for hay four or five times each year. Wide-row spacings permitted haying operations, but tree rows and turning areas removed 5 to 8 percent of the area from production. However, hay yields and liveweight gains by yearling cattle were near normal for this locale. Slash pine planted in these fertilized pastures survived well, grew rapidly, and only a few trees were killed during haying operations. After 6 years, 83 percent of the trees survived and averaged 6.5 m in height and 13.2 cm in diameter. Cattle killed a few trees by rubbing during the 4th year. Wide-row spacing of pines permits harvesting forage for hay while waiting for the trees to become large enough to permit grazing. This approach to agroforestry produces annual returns to the landowner while awaiting maturity of the pines.     

Multiple use of water: integration of fish culture and tree growing

Red tilapia (hybridOreochromis mossambicus x O. urolepis hornorum) were raised in pulsed flow irrigation systems in which water subsequently used to irrigate mesquite trees (Prosopis granulosa).The increase in height and stem base area was significantly greater (P<0.001) in mesquite trees irrigated with water from the fish culture facility than in mesquite trees irrigated with well water. Trees irrigated with water from the fish facility could be sold after about six months for prices ranging from $5.50 to $8.50. Trees irrigated with well water took twice as long to reach a marketable size.The Unit is jointly sponsored by the US Fish and Wildlife Service, Arizona Game and Fish, and the University of Arizona.     

A study of alley-cropping data from Northern Brazil. I. Distributional properties

Measurements from trees and plants of a BrazilianInga/maize/beans alleycrop experiment were assessed for their distributional properties for three years of the study. Results for the tree data were similar to those found in an earlier study. Results for the crop data demonstrated similarities between the distributions for alleycrops and solecrops, nonnormality shown by positive skewness and peaked distributions. Changes in the distributional shapes were demonstrated from year to year as soil nutrient depletion increased and as climatic variables fluctuated. Variation across the rows in the alley was often of a similar size to variation from plant to plant within the rows. Initial recommendations for analysis of such data are given on the basis of these results.     

Agroforestry: southern pines and subterranean clover cultural treatments

Agroforestry research in central Louisiana, USA, examined the effects of agronomic cultural treatments (disk, chemical, hay, and hay-graze) on subterranean clover (Trifolium subterraneum L.) yields and slash pine (Pinus elliottii Engelm.) and loblolly pine (P. taeda L.) survival and growth. Cultural treatments appear necessary for successful production of subterranean clover in tame pastures, especially for early fall forage growth. Subterranean clover yields in volunteer swards during spring were highest on the disk and chemical treatments. Generally, pine survival and growth during the first 5 years following tree establishment were not affected by cultural treatments.     

Root development in a Sesbania sesban fallow-maize system in Eastern Zambia

Roots of trees (Sesbania sesban) and crops (Zea mays) were quantified during two tree/crop cycles in a sequential tree — crop system at Chipata, Eastern Zambia. The experiment included one- and two-year fallows as well as fertilized and unfertilized controls. The roots of S. sesban represent a standing biomass in the soil of 3 Mg ha^t-1 in the top 1.5 m after two years, with 45–60% and 70–75% being in the top 25 and 50 cm respectively. S. sesban fallow improved early rooting and growth of the following maize crop. Increased soil infiltration was also observed in the two-year fallow treatment, as well as decreased bulk density and resistance to penetration in the soil. No differences between maize root parameters could be detected at tasselling, nor differences between nutrient status of the different treatments. Study results indicate that under the drought-prone conditions of Eastern Zambia, where improved soil physical conditions are important for early deep rooting of crops and access to water and nutrients, tree roots could play an important role in the fallow effect. Further studies are required to assess the relative importance of the improvement of soil chemical and physical properties.Submitted as ICRAF Journal Article # 95/28.     

Tropical floodplain agroforestry systems in mid-Orinoco River basin,Venezuela

Agricultural studies in seasonally flooded areas in the tropics have been limited. Orinoco alluvial soils are more fertile than adjacent non-flooded soils, and have been considered as potential areas for further agricultural development. Traditional agroforestry practices offer some possibilities to overcome the most limiting factors of floodplain cultivation. Indigenous knowledge of these traditional agroforestry practices was assessed and some indicators of the system's nitrogen and biomass dynamics were monitored. Nitrogen inputs by sediment and plant residues were 1668 and 47 kg ha^–1, respectively. Traditional selection of sediment by tree-and-grass barriers and litter management strategies increase nutrient-use efficiency in floodplain agroecosystems.

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Resumen Estudios agrícolas en areas tropicales sujetas a inundación estacional han sido limitados. Los suelos aluviales o vegas del Orinoco son más fértiles que suelos cercanos no sujetos a inundación y por lo tanto han sido considerados como areas potenciales para desarrollos agrícolas. Prácticas tradicionales de agroforestería constituyen una alternativa en el control de importantes factores limitantes en la agricultura de vegas. El conocimiento técnico autóctono asociado con prácticas agroforestales tradicionales de vegas fue evaluado y algunos indicadores de la dinámica de nitrógeno y biomas adel sistema fueron monitoreados. La contribución de nitrógeno por sedimentos y hojarasca fue de 1668 and 47 kg ha^–1 respectivamente. La selección del tipo de sedimento a depositarse en la parcela agrícola, por medio de barreras de vegetación, y el manejo adecuado de resíduos orgánicos constituyen estrategias tradicionales que aumentan la eficiencia de uso de nutrientes en sistemas agrícolas de vegas.

     

Timber harvest,damage to crop plants and yield reduction in two Costa Rican coffee plantations with Cordia alliodora shade trees

Both model and field estimations were made of the damage inflicted to coffee plants due to the harvest of timber shade trees (Cordia alliodora) in coffee plantations. Economic analyses were made for different coffee planting densities, yields, and both coffee and timber prices.Damage due to tree felling and log skidding should not be a major limitation to the use of timber shade trees in coffee plantations. The timber price that would balance all discounted losses and benefits to zero, for scenarios with and without trees ranged between 8–20 US $/m³ (current overbark log volume at the saw mill yard is US$ 66/m³). There will be lower margins for coffee damage in high yielding plantations, specially in years of good coffee prices. Nevertheless, the use of timber shade trees is recommended even in these scenarios.