Cytisus proliferus

Australia

The potential of tagasaste as a Spanish fodder was identified by Dr Perez, a medical practitioner, based on La Palma island in the Canary Islands in the 1870s, and Spanish cattle farmers. He wrote to the Spanish authorities promoting tagasaste as a fodder shrub but could not get them interested. He then sent seed to Kew Gardens in England. Kew Gardens tested tagasaste and then sent seed to all its colonies around the world. In Australia, tagasaste's potential was promoted by a number of individuals over the next century (e.g. Dr Schomburge in South Australia and Dr Laurie Snook in Western Australia) but was not adopted on a large scale until the 1980s in Western Australia.

The first 2 ha of tagasaste in the West Midlands was planted by John Cook on his farm near Dandaragan in 1982. The success of this small paddock excited the interest of local farmers and researchers. Before this the farming systems in the region were totally based on annual pastures and crops. The region has strongly winter dominant rainfall, with up to eight months without rain over some summers. Until the development of tagasaste it was believed it was not possible to grow perennial pastures in this region.

In 1984 the Martindale Research Project was started by the University of Western Australia with a large grant from Sir James McCusker. This project encouraged the participation of local farmers and the Western Australia Department of Agriculture in research and development. Farmers such as John Cook and Bob Wilson at Lancelin developed seeding and mechanical cutting equipment that allowed tagasaste to be sown and managed cheaply by farmers on a broadacre scale. The Martindale Research Project resolved many issues relating to agronomy, animal production and economics that resulted in a reliable package that farmers could adopt with confidence. The Western Australia Department of Agriculture also conducted trials on their Badgingarra Research Station and at Bob Wilson's farm at Lancelin. Local farmers and researchers formed the West Midlands Fodder Shrub Improvement Group. This evolved into the Evergreen Group,^[6] which expanded its interests to include a range of other shrubs, grasses and perennial legumes.

There are now about 100,000 ha of tagasaste in Western Australia. In Western Australia it is mostly grown on deep, infertile sands in regions nearer the coast with 350 to 600 mm rainfall. Most of the tagasaste in Western Australia is in the West Midlands sand plain to the north of Perth.

New Zealand

The use of tagasaste as a fodder crop was identified as early as 1897 in the Taranaki Region.^[7] As of 2011 it is still recommended as a fodder crop in some parts of the country but it also is becoming an invasive species. The Department of Conservation, a government agency responsible for protecting public conservation land, considers tagasaste to be an "environmental weed".^[8]

Africa

in Africa, tagasaste is commonly known as tree lucerne and Chamaecytisus Palmensis. Australia and New Zealand make use of an extensive approach employing tagasaste or tree lucerne on a broadacre commercial scale mainly for in situ grazing by livestock. In sub-Saharan Africa, South Africa is the only country following this extensive commercial livestock model using tree lucerne. In Nigeria, Rwanda, Burundi, Tanzania, Kenya, Uganda and Ethiopia the approach is mostly intensive among small-scale subsistence farmers on very small plots of land, typically 1 hectare or less. The main focus is using tree lucerne for subsistence, quality of life and protein dietary purposes, with surpluses going to the commercial markets. The goal is to first to feed the family with protein (mainly eggs, milk, chicken and goats), with cash crops raised between rows of tree lucerne, with the balance of surplus production going to the market for cash income. Tree lucerne is thus attractive to poor small-scale subsistence farmers who have entrepreneurial flair, and have a need for dietary support and income enhancement. Its main contribution is as a fertilizer replacement and high value fodder substitute.

High population pressure and lack of land, problems with deforestation resulting in lack of firewood, and overgrazing on communal grazing all result in intense cultivation of tree lucerne on 1 hectare plots for a variety of reasons. The low-protein calorie intake of small-scale subsistence farmers stuck in a soil poverty cycle (unable to afford fertilizer for higher crop yields and unable to fallow land) can be addressed by tree lucerne as a nitrogen fixing tree. The key challenge of dirt poor subsistence farmers is that the soil nutrients are leached from their soil by tropical rain and year on year production without fallowing. The lack of soil nitrogen is the main production constraint, with these countries unable to produce their own nitrogen fertilizers and thus financially unable to replace lost soil nitrogen leached by rain and extracted by continuous production. This leads to severe soil poverty and a cycle of low harvest yields.

Import of fertilizer plus transport cost typically results in a cost of pure nitrogen fertilizer costing roughly $1 per kg on a retail level. The lack of foreign currency results in an inability to properly replace lost soil nitrogen, locking such dirt-poor farmers into a perpetual poverty cycle. Tree lucerne as a nitrogen fixing tree is able to harvest more than half a ton of free atmospheric nitrogen, per hectare, per year, if planted at plantation density in alley crop rows on 1/3 of a hectare, with 2/3 of the hectare planted to cash crops in the interrows. This intercropping approach is very similar to the short lived tree Sesbania sesban. The intercropping using tree lucerne results in potential production increases to commercial production levels, although the biological fertilisation benefits typically only kicks in from month 24 onwards, with the first substantial commercial crop yield benefit at the end of year three. Tree Lucerne is a sustainable biological approach to soil fertility, especially if combined with terra preta. 40 kg of nitrogen per hectare per year typically yields 1 ton of maize, 200 kg of N yields 4 tons and 400 kg of N close to 8 tons, per hectare, per year. The ability of tree lucerne to fix 587 kg of free atmospheric nitrogen per ha/year is thus very attractive to remote rural farmers locked in a soil poverty cycle.

The chief benefit of tree lucerne is its ability to increase soil productivity roughly five times over five years and up to ten times over ten years, in deep well-drained soils mainly limited in nitrogen such as those found in the Great Rift Valley of East Africa. The 15-28% tree lucerne plant protein is converted into other forms of protein such as eggs, milk, white meat (chicken) and red meat (ruminants and cattle). This is mainly done by combining the need for land demarcation (hedgerows and windbreaks) with the ability to produce "high up in the air" (vertical expansion) due to the tree-like vertical growth of the tree lucerne hedgerow of 6–10 meters high to where there is available space horizontally. The side of the hedgerow is then harvested by hand until it forms a flat surface, using a machete for trimming, often standing on step ladders. The 6 meter high tree lucerne hedgerows (typically 1–3 meters wide) yield the same nutritional value as normal alfalfa (which is only 50 cm high). The lack of space for horizontal sideway expansion close to the ground forced such land limited farmers to expand vertically, going up in the air, in order to find more space. This approach allows them to achieve multiple production benefits and a 5-10 time production increase, over time, due to nitrogen fixation, soil improvement and terra preta bio-char amendments and the physical tree-like structure of tree lucerne (growing up, and expanding sideways, high up in the air, where there is space for sideways lateral branches, photosynthesis and sideshoot development).

This vertical expansion allows pruning of branches which are first eaten by livestock, eating the soft shoots and stripping the thicker material of bark, with the remaining wood then dried in the sun over a few days, for use as firewood and tinder, or used to produce high calorific value charcoal. Tree lucerne is a much desired species for charcoal production, with some of the bio-char used as a soil amendment, or for cooking and heating purposes. It has been found that tree lucerne charcoal is a good terra preta soil enhancer, able to prevent leaching of nitrogen and as a microbial breeding ground. The sale of charcoal is leading to older bigger Tree lucerne trees disappearing to this trade. Grazing pressure generally prevents tree lucerne becoming an invasive species in high-population, high-grazing density areas with high rainfall above 1200mm. Tree lucerne has not become invasive in Africa due to grazing pressure in a free range environment without fences. In remote locations with few people, the higher animal predation density in Africa has kept the plant from becoming invasive even in remote tropical highland areas. General deforestation is a driver for its establishment as it is one of the fastest growing trees in East Africa. A driver for popular uptake is that tree lucerne can be grown in residential and semi-residential areas as a boundary fence, ostensibly for aesthetic purposes, while in reality it is dual use - primarily for dietary support to feed chickens, milk goats and the like, which then benefit from increased egg production and enhanced milk production due to the alfalfa quality fodder harvested from a "living" haystack. Tree lucerne has also been found to make excellent fish food for koi and carp species.

Tree lucerne is also used in mountainous terrain, highlands and marginal areas that are of low agricultural value to normal alfalfa and cash crop production and therefore still available. Tree lucerne grow svery well on sloped land as the deep taproot is able to anchor land otherwise prone to erosion under cultivation. The combination of alley cropping with tree lucerne on heavily sloped land enables less suitable blocks of available agricultural land to be farmed effectively in an intensive model, although it takes two to three years for the biological fertilisation to become effective and is labour-intensive. Tree lucerne is very valuable as high-value nectar and pollen bee forage,^[9] and is used by small and large scale bee farmers.

Tree lucerne is used extensively by small-scale dairy farmers in East Africa, for its ability to enable commercial milk production levels on a small plot of land planted with a living fence of self-replacing tree lucerne. It is seen as a low-cost, self-grown alternative to dairy meal and alfalfa pellets. Tree lucerne is used as a boundary fence and hedgerow, acting as a windbreak aimed at stopping fire and wind, and yielding privacy, fodder, and firewood. Branches are typically lopped off by hand, and fed to grazing animals that may typically include 1-3 goats (milk and meat), half a dozen chickens (eggs), 1-2 calves (feedlot fattening) and 1-2 dairy cows, all on one hectare of land. Tree lucerne may be used to fence the property and the house, with the cash crop grown between alleys of tree lucerne. Tree lucerne is thus used extensively for purposes of biological fertilisation and soil improvement utilizing the alley crop method whereby vegetables, as well as cash crops such as tobacco and maize are planted in the interrow from year three onwards. As one of the fastest growing trees in East Africa the need for firewood for consumption is a major driver for uptake, with the fodder and fence ability of secondary value. This is now changing due to the discovery^[10] that tree lucerne can fix up to587 kg of nitrogen per hectare per year,^[11] roughly half below ground by nitrogen fixation and roughly half when the plant is kept in a permanent juvenile state by lopping off alley crop branches at waist level and using it either as livestock feed (with manure then added as fertilizer and a nitrogen pathway) or with the branches put on top of the soil and covered with soil as a "green manure". Over time substantial increases in crop yields have been achieved this way, in the order of raising 1 ton of maize production to 8-10 tons, and 700 kg of burley tobacco to 3-3.5 tons, per hectare, per year. The level of biological fertilisation achieved by tree lucerne is at the top end of that found in the legume family, and typically consist of about 30-50 grams of nitrogen per meter of row. The use of tree lucerne for terra preta purposes was pioneered in Central East Africa on Oxisoil.

Cultivars

In Australia a prostrate form of tagasaste has been developed by selection, called Weeping Tagasaste.^[12] It is hoped that this plant will not require mechanical cutting or pruning. It is too early to say whether Weeping Tagasaste will yield the same production levels as that of normal tagasaste. Initial indicators are that production is lower and that the plant may be more vulnerable to soil disease.

In South Africa three cultivars have been trademarked: "Green Kalahari"^[13] for arid areas (300-500mm), "Cattle Candy"^[14] for temperate areas (600-800mm) and "Kilimanjaro"^[15] cultivar for tropical highland areas (800-3500mm) of rain. commercial breeding of tree lucerne cultivars have led to improved varieties with increased hardiness, disease resistance and a wider range of growing conditions and applications. The use of tree lucerne for silvopasture agroforestry as a companion crop is one example of dual use of the same land for increased production. Sheep are then used to suppress weeds and keep the tree lucerne in check, preventing it from shadowing out the main forestry crop. The biological fertilisation is enhanced with green manure and trampling, improving the soil over time, and leading to production increases. The Meatmaster sheep breed is an ideal ruminant for use on tree lucerne in agroforestry silvopasture applications.