Crop rotation with legumes Chile - Rotación de cultivos con leguminosas (Spanish)

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1 Crop rotation with legumes Chile - Rotación de cultivos con leguminosas (Spanish) Biological Nitrogen Fixation (BNF) of legumes as a source of N in crop rotations with cereals in Mediterranean Chile In the past, legumes were commonly used as a biological and economic source of N for farming systems. Nowadays, N-fixing legumes have been recovering as viable crops because of the increased cost of N fertilizer and the need to develop more sustainable farming systems. These systems combine phases of legumes of different duration, in which N is fixed and accumulates in the soil, followed by phases of cereal growing during which accumulated N is extracted In this new rotation for rainfed agricultural systems in Central Chile, four legume-wheat rotations were compared to a monoculture crop rotation (wheat followed by oat). The legume species are: the narrow-leaf lupin (Lupinus angustifolium); Wonga (early-flowering and high-yielding narrow-leafed lupin variety), yellow lupin (Lupinus luteus); Motiv, Peas (Pisum sativum); Rocket and a fodder mixture of vetch (Vicia atropurpurea) with oats. Legume seeds were inoculated with a specific Rhizobium. In the year following the legume crop, wheat was seeded without N fertilisation on the incorporated residues of grain legumes and green manure (vetch with oats). The BNF in the grain legumes varies from 124 to 178 kg N ha-1, depending on the type of legume. Peas are the most efficient fixing legume crop. In the lupins - wheat (L. angustifolius) rotation without application of N to the wheat after lupins, production of wheat was between 79 and 110% of that when fertilised with N. In the peas - wheat rotation, a yield equivalent to 72 and 105% of the wheat fully fertilised with N was obtained. While peas (Pisum sativum) can be eaten as a green vegetable, lupins and Vicia are used as fodder supplements for animals. The new rotations were developed and evaluated experimentally. Then, through a technology transfer programme, the technology was transferred to real conditions with farmers in a programme covering 250 ha in the municipality of Yumbel. The area has a subhumid Mediterranean climate with an average annual precipitation of 695 mm (80% concentrated in winter), with five months of drought. Soils are Alfisols of the Cauquenes type, classified as Ultic Palexeralfs. The soil is formed from weathered granite with moderately acidic conditions and low organic carbon. Clay content in the soil is 15% at depths of 0-18 cm depth. Below this depth, it is above 44%. The topography comprises a hillslope with a gradient of % and the main traditional crop rotation is oat-wheat or wheat-natural pasture. The farmers are smallholders working on their own land. The sizes of the holdings on the dryland soils vary from 5 to 20 ha. left: Wheat in the crop rotation after peas (Photo: Soledad Espinoza) right: Peas in the crop rotation (Photo: Carlos Ovalle) Location: Cauquenes and Bíobio Region: Secano interior, Mediterranean Chile Technology area: 250 km 2 Conservation measure: agronomic Stage of intervention: prevention of land degradation, mitigation / reduction of land degradation Origin: Developed through experiments / research, recent (<10 years ago); externally / introduced through project, recent (<10 years ago) Land use type: Cropland: Annual cropping Climate: subhumid, temperate WOCAT database reference: T_CHL002en Related approach: Compiled by: Carlos Ovalle, INIA - Instituto de Investigaciones Agropecuarias - Chile Date: Contact person: Carlos Ovalle, Instituto de Investigaciones Agropecuarias. covalle@inia.cl Classification Land use problems: - In rainfed areas of the Mediterranean region of Chile, bread wheat (Triticum aestivum) is mainly produced in rotation with oats (Avena sativa) and therefore N is obtained from the soil and synthetic N fertilizers applied during sowing and ploughing. These intensive crop rotations have resulted in deterioration of the physical properties and a depletion of soil fertility as a result of the drastic reduction in organic matter content of these soils. (expert's point of view)

2 Land use Climate Degradation Conservation measure Annual cropping subhumid Chemical soil deterioration: fertility decline and reduced organic matter content Agronomic: Vegetation/soil cover Stage of intervention Origin Level of technical knowledge Prevention Mitigation / Reduction Rehabilitation Land users initiative Experiments / Research: recent (<10 years ago) Externally introduced: recent (<10 years ago) Agricultural advisor Land user Main causes of land degradation: Direct causes - Human induced: soil management Direct causes - Natural: change in temperature, change of seasonal rainfall, Heavy / extreme rainfall (intensity/amounts) Indirect causes: education, access to knowledge and support services Main technical functions: - increase in organic matter - increase in nutrient availability (supply, recycling, ) - promotion of new crops and varieties Secondary technical functions: - improvement of ground cover Environment Natural Environment Average annual rainfall (mm) Altitude (m a.s.l.) Landform Slope (%) > 4000 mm mm mm mm mm mm mm mm < 250 mm > <100 plateau / plains ridges mountain slopes hill slopes footslopes valley floors flat gentle moderate rolling hilly steep very steep Soil depth (cm) >120 Growing season(s): 180 days(mar - Nov) Soil texture: fine / heavy (clay) Soil fertility: very low Topsoil organic matter: low (<1%) Soil drainage/infiltration: poor (eg sealing /crusting) Soil water storage capacity: very low Ground water table: 5-50 m Availability of surface water: poor / none Water quality: good drinking water Biodiversity: low Tolerant of climatic extremes: temperature increase, seasonal rainfall increase Sensitive to climatic extremes: droughts / dry spells If sensitive, what modifications were made / are possible: This technology should be complemented with no tillage and subsoiling of the soil (see QT CHL01). Human Environment Cropland per household (ha) < ,000 1,000-10,000 >10,000 Land user: Individual / household, mainly men Population density: persons/km2 Annual population growth: < 0.5% Land ownership: individual, not titled Land use rights: individual Water use rights: individual Relative level of wealth: poor, which represents 80% of the land users; 60% of the total area is owned by poor land users Importance of off-farm income: > 50% of all income: Access to service and infrastructure: moderate: health, technical assistance, employment (eg off-farm), roads & transport; high: energy, drinking water and sanitation Market orientation: mixed (subsistence and commercial) Mechanization: Livestock grazing on cropland:

3 Technical drawing Lupins forming part of the crop sequence (Lupinus angustifolium) (Soledad Espinoza) Implementation activities, inputs and costs Establishment activities - none Maintenance/recurrent activities - Seeding legumes - Application of fertilizer - Harvesting with special machinery Maintenance/recurrent inputs and costs per ha per year Inputs Costs (US$) % met by land user Labour % Equipment - rent seeder machine+harvesting % Agricultural - seeds % TOTAL % Remarks: There are not establishment inputs and costs because in annual crops all the cost are recurrent Assessment

4 Impacts of the Technology Production and socio-economic benefits increased crop yield increased fodder production increased fodder quality reduced risk of production failure increased farm income increased product diversification diversification of income sources (new products) Socio-cultural benefits improved conservation / erosion knowledge improved food security / self sufficiency improved health Ecological benefits increased biomass above ground C increased soil organic matter / below ground C reduced hazard towards adverse events improved soil cover increased nutrient cycling recharge reduced soil loss reduced soil crusting / sealing Off-site benefits Production and socio-economic disadvantages increased labour constraints Socio-cultural disadvantages Ecological disadvantages Off-site disadvantages reduced surface runoff increased water availability Contribution to human well-being / livelihoods Benefits /costs according to land user Benefits compared with costs short-term: long-term: Establishment positive positive Maintenance / recurrent positive positive Acceptance / adoption:. Hence it is expected that in the future the adoption of this technology increases up to 20,000 ha in the secano interior of south-central Chile Concluding statements Strengths and how to sustain/improve Weaknesses and how to overcome Reduces the costs of fertiliser: the incorporation of legumes in the rotation cycle means a saving of 30% of nitrogen fertilizer in cereal production costs keep the phases of legumes sufficiently frequent and long Increases the economic benefits. When analysing the whole farming system, replacing the traditional rotation of wheat followed by natural pasture, implies two economic benefits for the producer: increasing the income by the incorporation of a new crop (legumes) and the reduction of costs in the fertilization of cereals. Necessity of more training for the farmers improve / enhance agricultural extension Increase soil organic matter: the new rotation system means a new concept in the management of crop residues. These should be incorporated into the soil, which in the medium and long term will involve an increase in the soil organic matter content ensure application of the new management of crop residues The new rotation system involves an increase in productivity of the land, as it incorporates new cultures and improves the physical and chemical conditions of the soils.

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