Guidelines on Soil and Water Conservation (SWC)

Riceland (0 – 3% slope)

0-3% Slope: Riceland
Location: Villaverde, Nueva Vizcaya

This land use is suitable to very good land that covers alluvial or upland plains and river terrace. These areas can be cultivated safely and only requires simple but good agricultural practices. The area is either irrigated or rain-fed and considered as prime agricultural land suitable for field crop production (i.e. rice, corn, tobacco, ginger, etc.). Two cropping of rice followed by “mungo” for a third or dry season cropping is the recommended cropping pattern under irrigated areas. On the other hand, rice followed by leguminous crops (e.g. peanut, mungo, string beans) and/or vegetables is recommended in rain-fed areas.

Cropland (3 – 8% slope)

3 – 8% Slope: Alley Cropping or Hedgerow Intercropping
Location: Agoho, Tanay, Rizal

It is intended to gently sloping or undulating areas with slope range of 3 to 8 percent slopes. These areas are considered good land and can be used as expansion for rice production both for lowland and upland rice depending on the availability of irrigation water. It can also be utilized for upland crop cultivation particularly high value crops (HVC) by applying simple conservation and management practices.

Contour strip cropping is the simplest and the most suitable system that will lead to crop diversification in nearly level or gently sloping to undulating areas. Under the system, the field is divided into strips laid on the contour across the slope. The width of the strip depends on the slope of the land. Contour strip cropping involves the planting of two or more kind of crops in regular alternates. One strip is planted to forage or agricultural crops with close growing habit like sweet potato and the next strip is planted to row crops.

Modified cropland (8 – 18% slope)

8 – 18% Slope: Modified Cropland
Location: Albay, Province

This land use management option is recommended in undulating to rolling areas with slope range of 8 to 18 percent slopes. It is considered as a moderately good land but must be cultivated with caution and requires the application of carefully planned soil conservation measures to prevent soil erosion and maintain or improve soil fertility. In addition, these areas can be developed into a modified cropland for multiple cropping systems that involves cultivation of different kind of annual crops as described below:

Alley cropping with improved pasture grasses and/or fodder tree or shrub species as vegetative barrier. Under the system, pasture grass or legumes will be used as vegetative barrier to control soil erosion and provide a source of fodder for animals following a cut and carry system. Alleys between pasture grasses or shrubs used as vegetative barrier will be planted to different kinds of annual crops, preferably high value crops.

Alley cropping or hedgerow intercropping system. This involves the planting of leguminous tree or shrub species in double rows along the contour as vegetative barrier. The strips or alleys between hedgerows are planted to different kinds of annual crops. Under this system, the hedgerows are pruned regularly at the height of 0.5 meters to avoid shading of crops planted in the alley. Biomass of hedgerow can be used as source of green manures.

However, the adoption and use of leguminous tree or shrub species as vegetative barrier is very low. As an alternative, high value crops like pineapple can also be planted as vegetative barrier instead of leguminous trees or shrubs. Its effectiveness in mitigating soil erosion is comparable to trees and shrubs. It does not only prevent soil erosion but also serves as additional source of income for farmers. Another alternative is the use of natural vegetative strips (NVS) which is very simple and easy to establish.

Diversified cropland (18 -30% slope)

18 – 30% Slope: Diversified Cropland
Location: Duale, Limay, Bataan

This is intended to rolling areas with slopes ranging from 18 to 30 percent. Base on land capability classification, these areas are best suited for pasture or forest. It can also be utilized for cultivation but should be handled with extra caution. Cultivation of these areas requires very careful management and complex conservation practices. These areas can be developed by adopting farm-based agro-forestry system such as:

Hedgerow intercropping system. The system involves the establishment of hedgerows along the contour as buffer to control soil erosion. Alleys between hedgerows will be planted to both annual and perennial crops in alternate strip arrangement. Perennial crops like coffee, citrus and the likes will be planted in every third alley while the two alleys between it will be utilized for annual crops (upland rice and other HVC). Another option is to plant forage grasses or legumes to alleys intended for perennial crops as source of protein rich fodder. Fodder will be fed to animals by following a cut and carry system. This makes a spatial ratio of 20% NVS, 30% perennial crops or forage crops and 50% annuals.

Multi-storey cropping system. In this system, mixed species occupy different canopy levels, with the upper layers occupied by trees or other perennials that provide partial shades to agricultural crops (annuals or perennials) in the lower layers. This system is similar to the structure (multilayer) and composition (diverse species) of tropical rainforest. Examples are coconut-coffee-pineapple-banana (commonly found in Cavite), Albizia-coffee/cacao) commonly found in provinces of Mindanao) and home gardens (being practiced throughout the country).

This system can be adapted by inter-planting shade-tolerant species under established trees or coconut plantation.

Plantation/orchard and pasture (30 – 50% slope)

30 – 50% Plantation Orchard and Pasture
Location: Albay, Province

Steep portion with slope ranging from 30 to 50 percent slope is best suited for forest and pasture. However, it can be developed into plantation crops for exotic fruit trees and other permanent crops. This kind of terrain can be developed by adopting farm-based agro-forestry system coupled with soil conservation and management practices. Agro-forestry systems that can be adopted in developing the potential of these areas for agricultural production are:

Multi-storey system + animals. This is similar to the multi-storey system except that free range grazing animals are added as a component. An example of this is the coconut-lanzones mixture with horses or cattle, found in Laguna and Quezon province.

Forage legumes are planted under this system as nurse or cover crops while other permanent crops are still in seedling stage. Animals are only allowed to graze under the system when all the perennial crops are fully gown and cannot be destroyed by animals.

Improve pasture. This land use is suited in areas with slope range of 30 to 50 percent slope with shallow soil and have fertility problem, particularly near the river banks or water Alline of the reservoir. Under the system, hedgerows of fodder trees or shrubs (e.g. Desmodium rensoni, Leucaena leucocepala, Gliricidia sepium are planted along the contour line as hedgerows. The alleys between the hedgerows are planted with improved pasture or grasses and/or fodder legumes. Trimmings from hedgerows together with forage legumes planted between it will be used as source of protein rich fodder for animals. Fodder will be fed to animals in a cut and carry system.

Taungya system. It is an agro-forestry system in which newly established orchard or forest plantation areas are inter-planted with agricultural crops as source of income while waiting for the permanent crops to bear fruits or give harvest. As soon as the canopies of fruit trees close making the light intensity critically low for cultivated crops particularly annuals, it should be replaced with other crops usually perennial crops that require partial shade. Other option is to plant forage legumes as cover crops and soon serves as grazing for animals.

Forest or woodlot (>50% slope)

>50% Slope: Forest or Woodlot

Very steep slopes with more than 50% are often excessively eroded, shallow, rough or dry for cultivation and are best suited for forest or pasture with very careful management and definite restriction. With such limitations, this kind of terrain can be utilized best for forest and wildlife and must be protected. Thus, this kind of area should be rehabilitated to bring back its natural condition through enrichment planting of sparsely vegetated areas, replanting of damaged areas and/or saturation planting of indigenous species. When the trees are tall enough, they can be inter-planted with shade tolerant species like abaca, rattan, karagumoy and anahaw.

Protein or fodder bank (shallow soil and to the approach or above the water line/level of any rain water impounding structure)

Protein or fodder bank (shallow soil and to the approach or above the water line/level of any rain water impounding structure)
Location: San Jose, Mindoro Oriental

The protein or fodder bank is recommended to about 20 meters wide area along the approach or above the water line/level of any rain water impounding structure. It involves the intensive planting of fodder trees/shrubs and pasture grasses to a small area on the approach or above the water line of water impounding structure. It also involves the growing of leguminous fodder trees or shrubs (e.g. ipil-ipil, kakawate, Desmodium rensoni, Flamengia congesta, etc.) along the contour as hedgerows. The alleys between hedgerows are planted to improve pasture grasses. This area is planted intensively for maximum protein and rich fodder production. The top and side branches prunings are fed to the animals through the “cut and carry” system. Establishing this kind of vegetation provides a good cover on the approach or area above the water line of rain water harvesting structure, thus reducing siltation.

Contouring.

A central element of soil conservation particularly in sloping land is contouring. It involves the correct establishment of contour lines. If contour lines are incorrectly established they can increase soil erosion. Contour lines are used as guides in the establishment of hedgerows, fodder grass strips, natural vegetative strips (NVS), and drainage canals.

A contour is a line which runs across the hill slope in such a way that it stays at the same elevation and does not run up or downhill. Contour lines can be laid-out with the used of A-frame. Land which has not been cleared and cultivated is the best condition to work on. If the land has been cultivated, the site for placing the leg of the A-frame should be properly leveled with the foot.

The A-frame is a simple tool made from local materials (wooden or bamboo) for laying out contour lines across the slope. It is made of wooden or bamboo poles nailed or tied together in the shape of capital letter A, a string as the “line”, and a stone providing the weight to the line.

Contour strip cropping.

Contour Strip Cropping
Location: Tanay, Rizal

The practice is recommended to nearly level or gently sloping areas. It is the process of dividing the field into strips laid along the contour across the slope. The width of the strip depends on the slope gradient of the land and soil condition. Contour strip cropping involves the planting of two different kinds of crop in regular alternate strips in the field. One strip is planted to agricultural crops with a close growing habit and the next strip is planted to row crops. The practice is done so that when the soil is washed down from the row crop, it will be caught and trapped in the next strip of close growing crops. The planting of these crops should be rotated so that the strip used for row crop will be used for close-growing crops in the next season.

Buffer strip cropping or hedgerows

Pineapple as vegetative barrier
Location: Tanay, Rizal

This is the simplest erosion control practice in sloping land. It is an agro-forestry technique – which in its conventional form, involves the planting double row of nitrogen fixing trees or shrubs species (i.e. ipil-ipil, kakawate) along the contour line to slow down over land flow or surface runoff caused by rainfall. They also trap soil carried by runoff water, thus gradually form natural terrace. Its biomass serves as green manures that can improve soil fertility. It also serves as source of fodder and firewood. Furthermore, hedgerows improve soil structure and water infiltration.

However, adoption of this technology might become unpopular because hedgerows occupy almost 25 percent of the farm that reduce area for cultivation and source of income for small farmers. The solution to this problem of technology adoption is to use income generating crops (i.e. pineapple, black pepper, citrus, asparagus, rose) as alternative for tree or shrub species as hedgerows. As of today, using pineapple as buffer crops gain popularity to many farmers. This is considering that pineapple is not only comparable to leguminous trees or shrubs in mitigating erosion but is also a good source of additional income to farmer.

Another good alternative is NVS or grass strips These strips are live barriers vegetated by naturally growing grasses and herbs intentionally left unplowed along the contour of sloping land. These strips serve as buffer that prevents the soil from eroding by more than 90% during heavy rains and intensive cultivation. It is easy to establish. Establishment can be done during land preparation and requires minimal labor using the contour line laid out with A-frame as a guide. In addition, NVS provides farmers a good foundation to evolve their farms into complex agro-forestry system and increase productivity.

Improve fallow or alternate strip arrangement.

Improve fallow is the modification of traditional fallow or shifting cultivation methods of farming sloping land. The system involves planting of forage legumes and annual crops in alternate strip arrangement. The dense cover of forage legumes slows down runoff and trap sediments coming from the adjoining cleaned-tilled strips planted to agricultural crops. Strips or alleys with annual crops will be cultivated for two cropping season in a year. After two cropping season, alleys that are previously planted with annual crops will be left on fallow period for one year by replacing it with forage legumes as source of protein rich fodder for animals. With this the previously cultivated alley will be rested and can undergo rehabilitation. Thus, alley with forage legumes will be utilized for cultivation of annual crops.

Ridge terraces.

A ridge terrace consists of furrow and ridge, constructed along the contour of sloping land with slope less than 18 percent. Its purpose is to control runoff and trap eroded soils as well as nutrients. Intense rain can wash away ridges especially in the first two years when they are not firmly established. Thus, grasses and legumes are usually used to stabilize the ridge, but fruit trees, bananas and cassava are also commonly used. During wet season, the furrow fills with sediment rich in soil nutrients needed by the plants which can be put back along the cultivated area for fertility replenishment.

Soil barriers.

These are structural barriers made of woods or rocks to slow down runoff and retain the soil loss by sheet erosion. Barriers are constructed by filing rocks, stones, woods and root stuffs across the slope. Over time, natural terrace formation will develop and can be supported with live fences of trees and shrubs for stability.

Conservation tillage.

The maintenance of permanent soil cover of living or dead plant material is the heart of conservation tillage. Instead of the usual plowing and harrowing before planting, the crop seeds are drilled directly into the soil through the layer of crop residues. Conservation tillage results in a much shorter turn-around period between two cropping. This is very crucial towards dry planting season where there is limited rainfall as it takes advantage of the residual moisture at the end of rainy season.

Cover cropping.

It is the planting of close growing crops in the field or under trees and/or during fallow period of cultivated land. In planting cover crops, it is necessary that critical slope or those that cannot be planted to seasonal crops be planted with grasses and legumes as protective ground cover. Cover cropping could be done permanently or temporarily. Permanent cover cropping is a means of minimizing soil erosion in sloping lands devoted to orchard and similar usage. These crops are short term crops grown to protect the soil from raindrop impact and overland flow. Cover cropping is practiced to suppress weeds under plantation and to provide fodder for animals. Temporary cover cropping is the catch cropping or the planting of crops after the main crop is harvested. Cover crops can also be used to improve soil fertility quickly and to shorten fallow period.

Crop rotation.

Considering its widespread adoption, crop rotation is arguably the most important management practice. Various crop species are grown in sequence, one after another, in the same part of the farm or field. Generally, a grain crop should be followed by a legume; a shallow deep rooted crop should be followed by deep rooted crops. These cropping patterns can vary from year to year, but are designed to achieve common result; better soil physical and nutrient composition.

Each crop places a different demand on the soil in which it is grown. Likewise, each crop leaves some amount of beneficial residue or performs some action on the physical structure of the soil. A good crop rotation takes into account each crop’s characteristics-what it takes and gives back into the soil to improve its fertility.

Multiple cropping.

This refers to practice which increase crop productivity while providing better protection of the soil from erosion. The technique involves relay cropping or the planting of two or more annual crops with the second crops planted after the first crop has flowered or nearing its harvest. This is to allow the second crop to make use of the available moisture and provide continuous ground cover. It also involves sequential cropping the growing of two or more crop a year in sequence, and intercropping and/or mixed cropping which is the growing of one or more crops in between rows of other annual crops or under perennial crops like coconut in the same piece of land.

Farm residue management.

Most farmers still consider that crop residues as nuisance which interferes with their farming operation. Apart from depriving them the opportunity to recycle nutrients which could decrease fertilizer inputs, crop residue burning emits carbon dioxide (CO2) which contributes to global warming. But if this agricultural waste particularly crop residues will be manage and recycled, it will lessen the input costs and increase farm income. Through proper utilization or management of crop residues, part of nutrients that was absorbed and not consumed by the plants will be returned to the soil through:

Composting. It is the process of allowing crop residues or any farm wastes to decompose under more or less controlled conditions. Any farm wastes or residues can be composted into organic fertilizer in many ways by combining these materials in different proportion through pile method in a traditional or new method that uses compost activator.

Traditional method uses crop residues (e.g. rice straw, corn stalk, etc.) combined with leaves of ipil or kakawate, animal manure and garden soil. After piling crop residues, spread on top of it a similar amount or at least 5 centimeters thick of legume leaves, animal manure and garden soil. Repeat the procedure of piling until it reaches 1 to 1.5 meters in height. Addition of animal manure will narrow down C/N ratio of compost heap – hastening decomposition. Moisten the pile of compost materials and cover it with plastic to reduce water evaporation and volatilization of ammonia as well as maintained desired temperature or heat during decomposition. Turn over the pile every week for the first two weeks and after every two weeks until compost is matured and ready for used. Compost matures for 3 months under this method.

The new method of composting has the same procedure in piling compost materials as in the traditional way. The only difference is the used of Trichoderma harzianum as compost fungus activator (CFA). This CFA, is diluted to water and spray over every layers of compost materials to hasten its decomposition to only 30 days.

Residue incorporation. It can considerably increase the organic matter content of the soil and thus lessen the need for commercial fertilizer. This can be done by cutting and then spreading the crop residues evenly in the farm. This will also provide surface protection to the soil during the turn-around period when erosive rainfall occurs. During land preparation for the succeeding crop, the residue is incorporated into the soil. When decayed, this will increase the supply of nutrients improve soil structure, porosity and water holding capacity.

Mulching. It is a soil and water conservation practice in which covering of cut grass, crop residues or other organic materials is spread over the ground, between rows of plants or around the base of trees. The practice helps retain soil moisture, prevent weed growth and enhances soil structure. It also improved soil fertility when decayed. The choice of mulch depends on locally available materials.

In alley cropping system, hedgerow biomass is usually used as mulching materials. In orchard, cover crops serve as live mulch, especially around young trees that are well established. Another strategy is to leave crop residues on the ground after harvesting (e.g. pineapple tops, corn stalk, rice straw, etc.). This ensures that some nutrients are taken up by the plants and return to the soil.

Trash line. In steep sloping lands where soil erosion is a problem, farm residues (e.g. corn stalks, coconut leaves and husks, banana trunks) can be used as trash line piled along the contour. This will enhance water infiltration, slows down runoff and minimizes soil loss. When decayed, the residues will provide nutrients, lessening the need for synthetic fertilizers. Trash line is best under coconut plantations and orchard.

Modified rapid composting (MRC). This is a new practice of rehabilitating or improving the soil condition in rice area particularly irrigated land. The practice improves the fertility condition of paddy field by returning and/or composting rice straw right on the farm. The practice involves the spreading of rice straw evenly on the farm. After spreading, rice straw will be soaked over-night by irrigating the field before spraying Trichoderma harzianum to enhance decomposition. Under the practice, rice straw can be decomposed after 21 days – field was rested and can be prepared for planting. Furthermore, the practice is cost effective and environment friendly.

Brush dams.

Brush dams are supplemental structure established in a localized portion of the farm with gullies. These are made of rocks, woods, bamboos or any indigenous materials available in the farm. The materials are constructed as temporary structure-like dam to prevent or stabilize gully formation.

The brush dams are constructed into the small gullies with 150 x 60 centimeters in size that starts at its very head. The gully should be lined first with small branches to protect the soil. The brush fill should be stand-up above the gully banks so it can be weighed down with rocks or heavier limbs and to allow for brush shrinkage. The objective is to obliterate the gully with the soils held by the brush.

Wind breaks.

Wind breaks are established by planting three (3) rows of forest or fruit trees along the border or perimeter boundary of farm lot. In large agricultural land or lot, it is established to counteract adverse ecological condition by reducing wind movement and velocity. It also serves as source of fuel wood and fodder for animals. Fully grown wind breaks can be inter-planted with rattan to provide additional benefit or source of income for farmers.

Small Farm Reservoir (SFR).

Small farm reservoir is suitable in elevated areas with depression to harvest and impound rain water. Sites that are commonly owned should be managed properly to ensure sharing among intended beneficiaries. Places with springs or flowing streams are good sites to ensure a year round water supply. Topography that is undulating or rolling with slope of 3 to 18% is desirable for SFR sites. It is built by excavating the soil in the depression and constructing dam or embankment of earth filled clayey soil. Reservoir embankment is provided by spillway to divert or drain excess water trap in the reservoir.

Rain water impounded in the reservoir will minimize the amount of surface runoff or overland flow – preventing soil erosion and localized flooding. Aside from minimizing soil erosion, SFR will serve as source of supplemental irrigation for crop production, fresh water aqua-culture, livestock drinking pond and duck raising.