Is the perennial lupin a weed, a invasive plant or a valuable plant?
Our answer is here in the following paper.
Perennial forms of Washington lupin (L. polyphyllus Lindl.) for effective use in Finland
Boguslav Kurlovich, Peter Earnshaw and Matti Varala
Perennial, multifoliate or Washington lupin (Lupinus. polyphyllus Lindl.), widely distributed in Finland, Poland, Belarus, Russia and other countries, was introduced into Europe as an ornamental plant and for green manure production purposes.
Here the natural populations of different perennial lupins were generated on the edges of woods and fields, on roadsides , and in parks and on the sites of former manors. It is very hard to remove wild lupin plants from the fields, as lupin has a potent assemblage of rootlets. This has allowed some experts to classify this plant as a malicious weed. But they do not know how to get rid of it. On this basis many ecologists consider it more expedient to cultivate only native indigenous plants in the Nordic countries , thus overlooking the fact that the potato, sunflower, maize and other valuable plants were introduced from the American continent, as were lupins.
We consider, as it is already practically impossible to eradicate perennial lupin from nature, it needs to be used effectively!
It can be cultivated on low-fertile sandy and acid soils, unprofitable for cultivating other crops. Under such conditions it can be grown and harvested for 4 to 6 years providing a yield of green mass up to 40-50 t/ha with 18-20% of protein (percent of dry matter).
However, this « barrel of honey contains a spoonful of tar». We mean the bitter alkaloids which render wild lupin not inedible for domestic animals.
To avoid restoration of alkaloid synthesis in cross-pollinated species of lupin, a new approach has been developed on the basis of specific crossing. Only compatible forms are involved in hybridization, with their low alkaloid content controlled by one and the same genetic system. These approaches have allowed transformation of this bitter weed into a valuable fodder crop.
Here the natural populations of different perennial lupins were generated on the edges of woods and fields, on roadsides , and in parks and on the sites of former manors. It is very hard to remove wild lupin plants from the fields, as lupin has a potent assemblage of rootlets. This has allowed some experts to classify this plant as a malicious weed. But they do not know how to get rid of it. On this basis many ecologists consider it more expedient to cultivate only native indigenous plants in the Nordic countries , thus overlooking the fact that the potato, sunflower, maize and other valuable plants were introduced from the American continent, as were lupins.
We consider, as it is already practically impossible to eradicate perennial lupin from nature, it needs to be used effectively!
It can be cultivated on low-fertile sandy and acid soils, unprofitable for cultivating other crops. Under such conditions it can be grown and harvested for 4 to 6 years providing a yield of green mass up to 40-50 t/ha with 18-20% of protein (percent of dry matter).
However, this « barrel of honey contains a spoonful of tar». We mean the bitter alkaloids which render wild lupin not inedible for domestic animals.
But now fodder (low alkaloidal or sweet) forms of this lupin species have been created!
This species of lupin has received the status of high-grade fodder crop as a result.
To avoid restoration of alkaloid synthesis in cross-pollinated species of lupin, a new approach has been developed on the basis of specific crossing. Only compatible forms are involved in hybridization, with their low alkaloid content controlled by one and the same genetic system. These approaches have allowed transformation of this bitter weed into a valuable fodder crop.
(The description of the developed methods is described in the following Post!)
Therefore, the introduction of perennial fodder (sweet) multifoliate Washington lupin into agricultural production will potentially allow a significant increase of soil fertility, production of protein-rich fodder and, consequently increased animal production. In the conditions of Northwest Russia positive results from the use of the sweet commercial variety of L. polyphyllus Lindl. «Pervenec» (first sweet variety), which is included in the State Catalogue of selection achievements of Russia.
Now breeding of sweet varieties of Perennial forms of Washington lupin is carried out in Finland.
The developed methods may also be applied to other cross-pollinated lupin species such as L. mutabilis Sweet, L. nootkatensis Donn., L. arboreus Sims., L. perennis L., L. elegans H.B.K., L. hartwegii Lindl. and other forms promising for agricultural production.
Perennial forms of Washington lupin (L. polyphyllus Lindl.) was widely popularized by Russian Academician Pryanishnikov (1931, 1962) who recommended this plant as the best source of green manure and it was advertised by Prof. G.Hill as the source of various forages and as a flower plant in New Zealand (Hill, 1988, 1994; Hill and Tesfaye, 1994). He proved that for reclamation of soils, especially poor in organic substances, it is necessary to apply sideral fertilizer, which not only improves soil properties but also raises efficiency of mineral fertilizers (Malygin, 1969). At present, when low-alkaloid (sweet) forms of lupins have been discovered, the prospect of complex utilization of this perennial species of lupin for fodder production, for green manure, in horticulture and in other fields seems quite promising.
Perennial multifoliate lupin (L. polyphyllus Lindl.) is a long-lived, multi-branching and leafy semi-shrub, 1.0 – 1.5 m in height. The natural populations of this species were generated in Finland and Russia on edges of woods and fields, on roadsides, and also in parks and on the sites of former manors. Its root system is strongly branched: separate roots reach a considerable depth. Every year buds are formed on the main stem and root collar, from which leaves and tall branch stems terminate in elongated flowering heads. Color of flowers is mainly dark blue, however they may include red, white and other shades.
Perennial types of lupins, and particularly multifoliate or ‘Washington lupin’ (Lupinus polyphyllus Lindl.), present a major interest for agricultural production. It can be grown for fodder and seed in countries with limited agricultural resources and a vegetation period insufficient for other lupin species, for example in Finland, and other northern countries.
Lupinus polyphyllus Lindl. provides a high yield of green mass during the period of acute deficiency in protein availability for livestock when other fodder crops have not ripened. Its green mass can be used efficiently not only as green fodder, but also for silage, hay and vitamin grass flour. The seeds ripen before the harvest of cereals.
In terms of green mass production, Washington lupin is in no way inferior and sometimes superior to clover and alfalfa. The lower is the soil fertility, the more obvious is the advantage of lupin as compared to the above mentioned forages.
Washington lupin can be successfully used as a means of increasing fertility of poor sandy soils, as it can enrich the soil with 250 to 300 kg/ha of nitrogen per annum. It can also be used to control soil erosion, especially in mountainous regions.
It is time for an introduction of this crop in Finland!
Features of cultivation of sweet Washington lupin for seed production.
Multifoliate lupin is a crop with specific requirements connected with its biological features. Non-observance of them results in a decrease of productivity, and sometimes in a complete failure. It is especially sensitive to the conditions of cultivation in the first year of life. On rapidly drying sandy soils where lupin is usually cultivated, long absence of precipitation results in severe loss of plant density. On heavy clay soils poor emergence can occur.
When suffering from lack of moisture, multifoliate lupin does not transfer superfluous moisture efficiently. In the process of development of the root system into the deeper layers of soil, lupin is less dependent on soil and climatic conditions than many other species. It also generally requires less of the soil nutrients. Lupin supplies itself with nitrogen from the activity of nodule bacteria, while potassium and phosphorus are acquired from deep-situated layers of soil with the help of its powerful root system. As with other leguminous crops, it consumes twice the potassium as it does phosphorus, and is intolerant of surplus of lime. It is necessary to plan that multifoliate lupin grows on one place for 4 – 6 years. In this connection, it is most expedient to place it on special sites. The best ground for this culture is sandy soils with mildly acid reaction (рН 5.5 – 6.5). It is not advised to plant multifoliate lupin on recently limed areas. Non-observance of this requirement can result in failure, as the plants of lupin react negatively to lime. It is necessary to apply the recommended rate of potassium and phosphatic fertilizers (К 80-120, Р б0-80 kg /ha) before sowing. The site is then harrowed and rolled.
The seeds of multifoliate lupin begin to sprout at a temperature of +2 – +30 C. Earliest shoots emerge at autumn or winter sowing at these temperatures. Lupin is very sensitive to the depth of sowing, which should not exceed 3 cm. Seeds will sprout even from the surface of the ground. Freshly harvested seeds are unable to sprout for some time, as they remain dormant. Their germination rate rises during 2 – 5 months after harvest in natural conditions. Thermal heating can considerably reduce this period.
The species has a property of grain hardness. At spring sowing with non-scarified seeds germination is uneven. Most seed does not germinate, even in months. It has been determined that seeds of lowest moisture content are the hardest. In this context scarification of seed is regarded as a mandatory method, especially at spring sowing. The best for spring sowing are scarified seeds provided by seed nurseries. However, in this instance the year is lost, as the majority of plants would only form bushes and develop a powerful root system, but during the period of vegetation they neither blossom, nor fructify. Only individual summer forms achieve in one year such complete maturity. More effective are autumn and even winter sowing, when fresh-cut seeds are subjected to air thermal heating without scarification. With the influence of low temperatures and humidity of the autumn, winter and spring periods, the shoots occur early in spring and seeds ripen by autumn. The summer sowing gives the worst results as the plants have no time to root and many of them do not survive the winter. In summary, perennial multifoliate lupin is best sown in the early spring or late autumn. Seeding rate depends on row spacing. At wide-row sowing (450 or 700 mm) it requires 8 – 10 kg / ha, with a distance of 4-6 cm between seeds in rows. In commercial production, with a sufficient supply of seeds, the seeding rate can be increased to 20 – 30 kg / ha. At conventional row spacing (140-180 mm) it requires 50 – 60 kg / ha. Perennial multifoliate lupin has high coefficient of duplication (from 1:100 up to 1:300), and these equations help to solve the problem of accelerated multiplication of new cultivars simply enough.
Flowering occurs usually in the second year from late May to early June, while maturing of seeds is observed in July till early August. This is much earlier than winter rye and summer grain cultivars. Populations of multifoliate lupin are non-uniform and the flowering and maturing of individual plants within the limits of a population vary widely. Maturing of seeds occurs at regular intervals in the flowering head. Shattering of pods occurs approximately 8 – 10 days after complete maturity. Either two-phase harvesting, or direct combining can be carried out depending on the ratio of the ripened and still ripening pods. It is necessary to note that unripe seeds harvested directly by a combine are, as a rule, unsuitable for sowing because of low germinating rate. At the same time, it is possible to receive positive results by separate two-phase harvesting. Unripe pods on the top of the flowering head ripen within several days in dry weather darken and become quite mature. Such seeds have a high germination rate. In very dry and hot weather, when seeds ripen rapidly in more or less regular intervals, it is possible to apply direct once-over harvest by combine. It should begin when unripe green pods remain only at the top of the cluster. The middle and the bottom part are quite ripe and begin to shatter. Under favorable conditions, perennial multifoliate lupins yield 1.0 – 1.6 t/ha.
Fodder low-alkaloid multifoliate Washington lupin is a perennial entomophilous plant. In view of this, for efficient seed production it seems reasonable to establish a special nursery for a term of many years, and to remove wild bitter lupin plants from the adjacent area. In the first year, all plants in the nursery need to be tested for the presence of alkaloids by pressing leaves and petioles against alkaloid-sensitive paper. All identified bitter plants should be removed before blossoming. Subsequently, such a nursery will satisfy the demand for seed for many years on greater areas.
The majority of agro technical requirements for cultivation of Washington lupin as forage are the same either for green manure or for seeds. The conventional (140-180 mm) row spacing developed for cereals is used for sowing of lupin in this case. Recommended seeding rate of seeds is 45 kg / ha. Harvest for fodder purposes (first mowing) will be carried out during phases of budding and flowering of the plants. After mowing, it is expedient to apply phosphorous and potassium fertilizers (10-20 kg equivalent of each element). This promotes the faster re-growth of the plants. During the summer it is possible to recover two harvests of green mass. The production of green weight of Washington lupin for the two cuts has been found in research by VIR to be on the average 60,2 t/ha over 3 years. The first cut averages 39,1 t/ha and the second 21,1 t/ha. The correct planting and management of lupin can thus provide a high yield of green fodder over 4 – 6 years. At the same time the fertility of the site under lupin is increased thanks to the nitrogen-fixing activity of Bradyrhizobium sp. (Lupinus).It is necessary to note that after plowing of old plantations of multifoliate lupin early in spring or autumn, the dormant buds emerge early on the roots of plants which produce too many seedlings which can survive to the next year. It is best to carry out the plowing of lupin in the beginning of a summer, in the early phase of flowering of the plants. The young buds are dormant at this time.
This species of lupin can be used as well as a pascual plant (for grazing).
There are different ways for utilization of perennial multifoliate lupin. They include: so-called moving form, reclamation of long-abandoned infertile land and sowing lupin with a companion crop and plowing in for the subsequent crop.
As a primary method of utilization of lupin, green matter is grown on one site, mown and transferred to another one, which needs to be developed and fertilized. Usually two mowings are made during a season. Commonly used are poor infertile grounds unsuitable for other crops, on which lupin will begin to grow. Sowing recommended in this case is without a cover crop, as its efficiency rises considerably after the first year. Perennial multifoliate lupin occupies a field for several years in this case. Cutting is carried out no later than full flowering; otherwise the second mowing will give insignificant dry matter. The first mowing is spread as fertiliser on a fallow field prior to sowing of winter crops. The second one is scheduled in autumn for potatoe and vegetable crops of the following year. The efficiency of a site under lupin strongly depends on soil conditions and fertilizers. The first mowing of lupin in the second year of life yields on the average about 25 t of green matter per hectare on light sandy soils. The second mowing yields much less and depends very much on meteorological conditions of the year. From the third year onwards the harvest of green matter at the first mowing would achieve 35 – 40 t and even 50 t/ha. Yields can be much higher on easily worked loamy soils. Each spring the plantation should be harrowed. On sandy soils it is possible to use one site for three or four years. Afterwards it will grow too thin and should be plowed up. Plowing is to be carried out in the end of spring or in early summer when lupin plants enter the flowering phase and viability of dormant buds expires. This would prevent the site from severe contamination in the next year. The most suitable subsequent crop is potato. The advantage of the so-called moving use of lupin as fertilizer is that the ground of the fertilized site is neither overdried, nor choked with growing young lupin plantlets.
Reclamation of long-fallow land involves restoring the fertility of poor soils and waste grounds. Lupin is grown on them for 3 – 4 years or more, then the land is plowed and made suitable for cultivation of other crops. Fertility of poor soils is restored best when perennial lupin is not mown for several years. However, it often happens that green matter harvested from a site under lupin is also used to fertilize other fields or that the crop is left standing in the field to increase plant density and seed yield. So, a site with lupin can be utilized for diverse purposes.
Agronomic requirements for creation of long-fallow land are the same as for cultivation of green manure. It is necessary to apply mineral fertilizer under lupin, harrow the crop every spring, and so on. When green matter is mowed on a long-fallow land, mowing should be accomplished no later than in August, so that lupin has enough time to collect nutrient substances before winter.
Lupin can be sown with a companion crop, eg barley or oats. In this case, perennial lupin is sown together with summer grain crops (barley or oats) and plowed in for green manure in the second year of life in May/June when the plants reach their flowering phase. A fertilized field can afterwards be used for planting vegetables, potatoes or winter crops. This method is efficient because lupin by itself does not occupy a field and no special treatment of soil is required. In this way lupin functions as a high value natural fertiliser.
Now breeding of sweet varieties of Perennial forms of Washington lupin is carried out in Finland.
The developed methods may also be applied to other cross-pollinated lupin species such as L. mutabilis Sweet, L. nootkatensis Donn., L. arboreus Sims., L. perennis L., L. elegans H.B.K., L. hartwegii Lindl. and other forms promising for agricultural production.
Perennial forms of Washington lupin (L. polyphyllus Lindl.) was widely popularized by Russian Academician Pryanishnikov (1931, 1962) who recommended this plant as the best source of green manure and it was advertised by Prof. G.Hill as the source of various forages and as a flower plant in New Zealand (Hill, 1988, 1994; Hill and Tesfaye, 1994). He proved that for reclamation of soils, especially poor in organic substances, it is necessary to apply sideral fertilizer, which not only improves soil properties but also raises efficiency of mineral fertilizers (Malygin, 1969). At present, when low-alkaloid (sweet) forms of lupins have been discovered, the prospect of complex utilization of this perennial species of lupin for fodder production, for green manure, in horticulture and in other fields seems quite promising.
Perennial multifoliate lupin (L. polyphyllus Lindl.) is a long-lived, multi-branching and leafy semi-shrub, 1.0 – 1.5 m in height. The natural populations of this species were generated in Finland and Russia on edges of woods and fields, on roadsides, and also in parks and on the sites of former manors. Its root system is strongly branched: separate roots reach a considerable depth. Every year buds are formed on the main stem and root collar, from which leaves and tall branch stems terminate in elongated flowering heads. Color of flowers is mainly dark blue, however they may include red, white and other shades.
Perennial types of lupins, and particularly multifoliate or ‘Washington lupin’ (Lupinus polyphyllus Lindl.), present a major interest for agricultural production. It can be grown for fodder and seed in countries with limited agricultural resources and a vegetation period insufficient for other lupin species, for example in Finland, and other northern countries.
Lupinus polyphyllus Lindl. provides a high yield of green mass during the period of acute deficiency in protein availability for livestock when other fodder crops have not ripened. Its green mass can be used efficiently not only as green fodder, but also for silage, hay and vitamin grass flour. The seeds ripen before the harvest of cereals.
In terms of green mass production, Washington lupin is in no way inferior and sometimes superior to clover and alfalfa. The lower is the soil fertility, the more obvious is the advantage of lupin as compared to the above mentioned forages.
Washington lupin can be successfully used as a means of increasing fertility of poor sandy soils, as it can enrich the soil with 250 to 300 kg/ha of nitrogen per annum. It can also be used to control soil erosion, especially in mountainous regions.
It is time for an introduction of this crop in Finland!
Features of cultivation of sweet Washington lupin for seed production.
Multifoliate lupin is a crop with specific requirements connected with its biological features. Non-observance of them results in a decrease of productivity, and sometimes in a complete failure. It is especially sensitive to the conditions of cultivation in the first year of life. On rapidly drying sandy soils where lupin is usually cultivated, long absence of precipitation results in severe loss of plant density. On heavy clay soils poor emergence can occur.
When suffering from lack of moisture, multifoliate lupin does not transfer superfluous moisture efficiently. In the process of development of the root system into the deeper layers of soil, lupin is less dependent on soil and climatic conditions than many other species. It also generally requires less of the soil nutrients. Lupin supplies itself with nitrogen from the activity of nodule bacteria, while potassium and phosphorus are acquired from deep-situated layers of soil with the help of its powerful root system. As with other leguminous crops, it consumes twice the potassium as it does phosphorus, and is intolerant of surplus of lime. It is necessary to plan that multifoliate lupin grows on one place for 4 – 6 years. In this connection, it is most expedient to place it on special sites. The best ground for this culture is sandy soils with mildly acid reaction (рН 5.5 – 6.5). It is not advised to plant multifoliate lupin on recently limed areas. Non-observance of this requirement can result in failure, as the plants of lupin react negatively to lime. It is necessary to apply the recommended rate of potassium and phosphatic fertilizers (К 80-120, Р б0-80 kg /ha) before sowing. The site is then harrowed and rolled.
The seeds of multifoliate lupin begin to sprout at a temperature of +2 – +30 C. Earliest shoots emerge at autumn or winter sowing at these temperatures. Lupin is very sensitive to the depth of sowing, which should not exceed 3 cm. Seeds will sprout even from the surface of the ground. Freshly harvested seeds are unable to sprout for some time, as they remain dormant. Their germination rate rises during 2 – 5 months after harvest in natural conditions. Thermal heating can considerably reduce this period.
The species has a property of grain hardness. At spring sowing with non-scarified seeds germination is uneven. Most seed does not germinate, even in months. It has been determined that seeds of lowest moisture content are the hardest. In this context scarification of seed is regarded as a mandatory method, especially at spring sowing. The best for spring sowing are scarified seeds provided by seed nurseries. However, in this instance the year is lost, as the majority of plants would only form bushes and develop a powerful root system, but during the period of vegetation they neither blossom, nor fructify. Only individual summer forms achieve in one year such complete maturity. More effective are autumn and even winter sowing, when fresh-cut seeds are subjected to air thermal heating without scarification. With the influence of low temperatures and humidity of the autumn, winter and spring periods, the shoots occur early in spring and seeds ripen by autumn. The summer sowing gives the worst results as the plants have no time to root and many of them do not survive the winter. In summary, perennial multifoliate lupin is best sown in the early spring or late autumn. Seeding rate depends on row spacing. At wide-row sowing (450 or 700 mm) it requires 8 – 10 kg / ha, with a distance of 4-6 cm between seeds in rows. In commercial production, with a sufficient supply of seeds, the seeding rate can be increased to 20 – 30 kg / ha. At conventional row spacing (140-180 mm) it requires 50 – 60 kg / ha. Perennial multifoliate lupin has high coefficient of duplication (from 1:100 up to 1:300), and these equations help to solve the problem of accelerated multiplication of new cultivars simply enough.
Flowering occurs usually in the second year from late May to early June, while maturing of seeds is observed in July till early August. This is much earlier than winter rye and summer grain cultivars. Populations of multifoliate lupin are non-uniform and the flowering and maturing of individual plants within the limits of a population vary widely. Maturing of seeds occurs at regular intervals in the flowering head. Shattering of pods occurs approximately 8 – 10 days after complete maturity. Either two-phase harvesting, or direct combining can be carried out depending on the ratio of the ripened and still ripening pods. It is necessary to note that unripe seeds harvested directly by a combine are, as a rule, unsuitable for sowing because of low germinating rate. At the same time, it is possible to receive positive results by separate two-phase harvesting. Unripe pods on the top of the flowering head ripen within several days in dry weather darken and become quite mature. Such seeds have a high germination rate. In very dry and hot weather, when seeds ripen rapidly in more or less regular intervals, it is possible to apply direct once-over harvest by combine. It should begin when unripe green pods remain only at the top of the cluster. The middle and the bottom part are quite ripe and begin to shatter. Under favorable conditions, perennial multifoliate lupins yield 1.0 – 1.6 t/ha.
Fodder low-alkaloid multifoliate Washington lupin is a perennial entomophilous plant. In view of this, for efficient seed production it seems reasonable to establish a special nursery for a term of many years, and to remove wild bitter lupin plants from the adjacent area. In the first year, all plants in the nursery need to be tested for the presence of alkaloids by pressing leaves and petioles against alkaloid-sensitive paper. All identified bitter plants should be removed before blossoming. Subsequently, such a nursery will satisfy the demand for seed for many years on greater areas.
Features of cultivation of sweet Washington lupin for fodder production purposes.
The majority of agro technical requirements for cultivation of Washington lupin as forage are the same either for green manure or for seeds. The conventional (140-180 mm) row spacing developed for cereals is used for sowing of lupin in this case. Recommended seeding rate of seeds is 45 kg / ha. Harvest for fodder purposes (first mowing) will be carried out during phases of budding and flowering of the plants. After mowing, it is expedient to apply phosphorous and potassium fertilizers (10-20 kg equivalent of each element). This promotes the faster re-growth of the plants. During the summer it is possible to recover two harvests of green mass. The production of green weight of Washington lupin for the two cuts has been found in research by VIR to be on the average 60,2 t/ha over 3 years. The first cut averages 39,1 t/ha and the second 21,1 t/ha. The correct planting and management of lupin can thus provide a high yield of green fodder over 4 – 6 years. At the same time the fertility of the site under lupin is increased thanks to the nitrogen-fixing activity of Bradyrhizobium sp. (Lupinus).It is necessary to note that after plowing of old plantations of multifoliate lupin early in spring or autumn, the dormant buds emerge early on the roots of plants which produce too many seedlings which can survive to the next year. It is best to carry out the plowing of lupin in the beginning of a summer, in the early phase of flowering of the plants. The young buds are dormant at this time.
This species of lupin can be used as well as a pascual plant (for grazing).
Cultivation and utilization of perennial multifoliate lupin for green manure.
There are different ways for utilization of perennial multifoliate lupin. They include: so-called moving form, reclamation of long-abandoned infertile land and sowing lupin with a companion crop and plowing in for the subsequent crop.
As a primary method of utilization of lupin, green matter is grown on one site, mown and transferred to another one, which needs to be developed and fertilized. Usually two mowings are made during a season. Commonly used are poor infertile grounds unsuitable for other crops, on which lupin will begin to grow. Sowing recommended in this case is without a cover crop, as its efficiency rises considerably after the first year. Perennial multifoliate lupin occupies a field for several years in this case. Cutting is carried out no later than full flowering; otherwise the second mowing will give insignificant dry matter. The first mowing is spread as fertiliser on a fallow field prior to sowing of winter crops. The second one is scheduled in autumn for potatoe and vegetable crops of the following year. The efficiency of a site under lupin strongly depends on soil conditions and fertilizers. The first mowing of lupin in the second year of life yields on the average about 25 t of green matter per hectare on light sandy soils. The second mowing yields much less and depends very much on meteorological conditions of the year. From the third year onwards the harvest of green matter at the first mowing would achieve 35 – 40 t and even 50 t/ha. Yields can be much higher on easily worked loamy soils. Each spring the plantation should be harrowed. On sandy soils it is possible to use one site for three or four years. Afterwards it will grow too thin and should be plowed up. Plowing is to be carried out in the end of spring or in early summer when lupin plants enter the flowering phase and viability of dormant buds expires. This would prevent the site from severe contamination in the next year. The most suitable subsequent crop is potato. The advantage of the so-called moving use of lupin as fertilizer is that the ground of the fertilized site is neither overdried, nor choked with growing young lupin plantlets.
Reclamation of long-fallow land involves restoring the fertility of poor soils and waste grounds. Lupin is grown on them for 3 – 4 years or more, then the land is plowed and made suitable for cultivation of other crops. Fertility of poor soils is restored best when perennial lupin is not mown for several years. However, it often happens that green matter harvested from a site under lupin is also used to fertilize other fields or that the crop is left standing in the field to increase plant density and seed yield. So, a site with lupin can be utilized for diverse purposes.
Agronomic requirements for creation of long-fallow land are the same as for cultivation of green manure. It is necessary to apply mineral fertilizer under lupin, harrow the crop every spring, and so on. When green matter is mowed on a long-fallow land, mowing should be accomplished no later than in August, so that lupin has enough time to collect nutrient substances before winter.
Lupin can be sown with a companion crop, eg barley or oats. In this case, perennial lupin is sown together with summer grain crops (barley or oats) and plowed in for green manure in the second year of life in May/June when the plants reach their flowering phase. A fertilized field can afterwards be used for planting vegetables, potatoes or winter crops. This method is efficient because lupin by itself does not occupy a field and no special treatment of soil is required. In this way lupin functions as a high value natural fertiliser.
Conclusion
Are perennial lupins weeds or valuable cultivated plants?
We consider, that L. polyphyllus Lindl. and interspecies hybrids between different species of lupins have the highest potential in Nordic countries and in Finland especially in future as a cultivated plants!
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Our book about lupins: «Lupins: geography, classification, genetic resources and breeding» it is possible to read on the Internet here, and also here!
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