Filosofía Institucional 1 Antecedentes históricos.

Upland farmers have two types of land holdings: (a) crop lands and (b) gardens. The typical upland holding consists of both cropped and fallow (1 to 3 years) fields. Garden lands are subdivided into three types: (b) home gardens, (c) river gardens and (d) tree plantation gardens. Home gardens are located near the house, while river gardens are narrow strips of land along the river bank (Fig. 4.2. It is noted that not every household has a river garden.

(a) (b) (c) (d)

FIG. 4.2. Examples of farmers’ land holdings in the northern uplands of Laos: (a) upland lowland continuum, (b) home gardens, (c) river gardens, and (d) tree plantation gardens [92].

Rainfed upland rice is grown much like wheat or maize in unbounded or bounded fields.

Rice fields are located on level, gently rolling, or steeply sloping topography, at elevations up to 2400 meters and with annual rainfall ranging from 1000 to 4500 mm. Uplands rice is grown

on highly fertile to highly weathered, infertile acidic soils. Only 15% of total upland rice is grown on fertile soils. Rainfed upland rice is cultivated under a variety of farming conditions – in shifting cultivation, in continually dry fields, and in alternating dry and wet fields (where rice begins as an upland crop and is harvested as a wetland crop). As a result, rainfed UR grain yields are highly variable from less than 1 t ha^-1 to more than 2.5 t ha^-1, with the overall mean yield being 1 t ha^-1. However, yields for upland rice can be increased by the development and use of improved varieties and by cultural practices designed to suit the local soil, climatic, and social conditions in different regions.

4.4.1. Traditional slash and burn shifting rice cultivation

Earlier, when villages were small and population density was low, 1–2 years of shifting cultivation with long (> 15 years) fallow periods was historically the dominant land use system.

Farmers grew upland rice either as a single crop, or rice mixed with other crops on mid slopes, using slash and burn methods (Fig. 4.3) [7]. For example, in Laos in 1990, an estimated 2.1 mha of uplands were under this type of shifting cultivation, with an annual cropped area of roughly 250 000 ha. This meant 1.8 mha was placed in regenerating bush fallows of varying length (1–19 years). In most mountainous regions of Asia there has been with their national government’s tacit support plus incentives, extensive deforestation, followed by removal of plant cover. Large concessions of land have been given for industrial plantations, or for mining.

These changes, together with shortened fallow periods have all contributed to the destruction of upland landscapes. They have also resulted in increased soil erosion, nutrient depleted and dried out soils, decimated soil organic matter, reduced soil microbial diversity, and an increase in infestation by weeds. As a result, upland areas planted to rice have diminished, and upland rice yields have steadily declined in Asia.

FIG. 4.3. Traditional slash and burn cultivation of upland rice, Northern Laos [6]

In traditional shifting cultivation, the brush is cleared from the land, the land is then ploughed once or twice, and rice seeds are broadcast or dibbled (with the help of a dibble stick).

Weeds are removed as and when necessary and mature rice panicles are harvested – all accomplished manually over a long period of 10 months for each year’s crop.

With increasing human population pressure being put on the land and the various national governments’ new land use policy to reduce fallow periods to 3–4 years between cropping, upland farmers are being forced to abandon their traditional shifting cultivation practices, which included long fallow periods. However, improvements have been suggested to replace shifting cultivation practices, including: permanent upland rice based farming systems; growing upland rice between rows of perennials including trees (agroforestry) or between contour planted live hedges; using reduced or zero tillage and crop residue management; adopting mixed or relay cropping to keep the vegetation cover over the soil for longer periods – up to most of the year;

the addition of plant ash instead of expensive lime to reduce soil acidity; and incorporating leguminous trees (e.g. Acioa barterii) within upland rice farms – the latter bringing up cations from subsoil layers to the surface soil through leaf litter.

4.4.2. Permanent diversified upland rice based farming systems

With use of the above measures, shifting cultivation with 3–5 year fallow periods now accounts for 14% of the Asian upland rice area, mainly in north eastern India, Lao PDR and Vietnam. Some 70% of the upland rice areas have instead become permanent diversified farming systems, ones where rice is grown every year and is closely integrated with other crops and livestock [1].

Among the four types of uplands (Section 3.4), the favorable uplands, which are situated on slopes less than 15%, and found near streams or just above valleys, are the most suitable habitats for continuous rice cultivation. Soils in some of these uplands are fairly rich in organic matter and nutrients. These high potential areas can thus be used for permanent intensive and commercial rice production [8]. However, to secure a sustainable productivity of upland rice under permanent cultivation, upland farmers utilise suitable cropping systems, like the rotation of the rice crop with other crops, multiple cropping, intercropping, mixed cropping, and alley cropping [9]. In locally adapted upland rice based cropping systems, crop yields, cropping intensity, and monetary returns increase, while risks of crop failure due to climate change or market swings are reduced substantially. Moreover, family nutrition and cash flow improves, due to increased availability of a mix of agricultural products for self-consumption or for sale.

Soil fertility is being enhanced by increased addition of crop residues, including N-rich legume residues. Even so, addition of organic manures and or composts and some amount of mineral fertilisers is necessary to maintain high yields of different crops in intensive upland rice based cropping systems.

Crop rotation: Upland rice is rotated with other crops such as maize, sorghum, beans, pigeon pea, mustard, Bengal gram, or safflower. The rotation of crops is one of the best ways to slow down or prevent the buildup of weeds, insect pests and diseases. In alternate years, upland fields are left fallow, or planted with green manure legumes like sunhemp, mucuna, sesbania or fodder legumes such as daincha. Such crop rotations will help build up soil fertility and reduce weed pressure in upland rice farms. Adequate nutrition of different crops in rotation is of course critical to maintain crop yields [10].

Intercropping: Planting 2 to 3 different crops in separate rows is defined as intercropping.

Upland rice is often intercropped with legumes such as pigeon pea, green gram, black gram, soy bean, or groundnut; with finger millet, maize, sunflower, or cassava [10]; and with maize, cocoa, or poplar trees (Fig. 4.4). For example, in the upland rice pigeon pea systems, farmers can plant one row of pigeon pea for every 10 rows of rice in row seeded crops [11]. Dry pigeon pea grains constitute a protein rich diet while pigeon pea residues will enrich the soil with organic matter and biologically fixed N.

(a) (b) (c) (d)

FIG. 4.4. Upland rice-based intercropping systems: (a) green gram; (b) maize; (c) Rice-cocoa; and (d) Rice-poplar trees (Source: 37a: [10]; 37b, c, d: By. V. Balasubramanian).

Mixed cropping: Mixed cropping refers to growing two or more crops simultaneously in the same field with no distinct row arrangement. This practice maximises land productivity, acts as an insurance against total crop failure, supplies multiple products for family consumption, provides a longer lasting vegetation cover to soil, and reduces pest pressure due to increases in on farm biodiversity. Crops planted in random mixture with upland rice include:

maize, sorghum, millets, job’s tear, sesame, cowpea, groundnut, pigeon pea, okra, yam, cocoyam, cassava, sweet potato, etc. [10]. For example, in upland rice pigeon pea systems in Laos, farmers mix rice seed (90%) with pigeon pea seed (10%) and broadcast the seed uniformly to establish mixed crops [11]. Crops are harvested as and when they mature. Use of judicious crop combinations, adequate fertilisation and weed control are necessary to maintain high yields of different crops over time.

Planting upland rice and other annual crops between rows of perennials or tree crops:

Upland rice is grown between rows of perennial crops such as banana, rubber, oil palm, coconut or cocoa during the establishment stages of the perennials, especially in Indonesia, Philippines and in parts of India. No crop is planted when the perennial crops grow and shade the ground completely. Only certain crops like banana, plantain, colocasia, yam and fodder sorghum or maize can be grown in fully developed tree plantations (Fig. 4.5).

(a) (b) (c)

FIG. 4.5. Annual crops planted between rows of coconut trees in Tamil Nadu, India: (a) banana, (b) colocasia, and (c) fodder sorghum or maize [6].

Growing upland rice on sloping lands: On steeply sloping lands (slope > 30%), no rice or annual crops are planted; rather these lands can be covered by planted forests. On other lands with a slope less than 30%, food crops like upland rice is kept to a minimum, just enough to meet subsistence needs. The remaining land can be left under perennial forage crops and or pasture for raising farm animals. Areas with a gentle slope and shallow to medium deep soils is selected for growing annual crops like upland rice; here again, rows of perennials, including trees, are planted along the contour to prevent soil erosion and to facilitate infiltration of rainwater into the soil (Fig. 4.6). Alternate crops like banana, plantain, and yam can be grown under partial shade of trees on slopes [10].

(a) (b)

FIG.4.6. Improved upland rice systems on sloping lands: (a) Agroforestry systems in which rice is grown between rows of perennials including trees and annuals; and (b) Upland rice growing between permanent live hedges established along contours of sloping uplands [10].

Conservation agriculture practices for upland rice farming: Cropping systems, based on direct seeding on permanent plant cover without soil tillage, seem to be a promising technique to tackle the challenges of soil and water conservation and environmental protection that traditional upland agriculture is facing in the tropics. Conservation agriculture (CA) practices like reduced or zero tillage and crop residue management will help farmers cultivate rice sustainably. Here, a planting stick is used to make holes on land covered with previous crop residues and rice seeds are dropped into the holes and covered with soil. Alternatively, a continuous slit is opened in rows and seeds are placed and covered with soil, leaving the

remaining land undisturbed. Weeds are often controlled by herbicides in zero till plots. In addition, adopting relay cropping will help keep the vegetation cover over the soil for longer periods or most part of the year [10].

Garden land farming: Garden lands near houses are used for vegetables (chili, cucumber, cabbage and coriander), cash crops (banana, pineapple, onion), and also for raising farm animals. River gardens are used mostly during the dry season when the water level in the river is low, exposing fertile strips where vegetable crops grow well. Fish are caught from the rivers for home consumption and for sale. On deep soils, farmers develop plantation gardens, where they plant teak, rubber, and or paper mulberry [6].

4.5. RICE PRODUCTION CONSTRAINTS IN RAINFED UPLAND RICE