Effectiveness of Root and Foliage Systems of Grasses used in Soil Conservation

Evaluation Of Effectiveness of Root and Foliage Systems of Grasses used in Soil Conservation in Paundi Khola Sub-Watershed

This research was carried out aiming at evaluating the root and foliage system of four grasses – Napier, Molasses, Stylo and Amliso. Rooting depth, Root lateral spread, foliage lateral spread, grass height, foliage cutting height, terrace riser slicing and erosion signs, insect/pest condition, local uses of grasses and farmers perception on different issues were measured in the field using direct measurement, direct observation, focus group discussion, key informants survey and semi-structured walk. The data were qualitatively and quantitatively analyzed to find the volume of soil bound by the roots, ground surface area protected by grass foliage, shading effect on cereal crops, spacing of grasses, effective terrace riser slicing height and quantity of planting material.

Terrace riser slicing practice is unavoidable but the quantity (height) of slicing can be minimized. Farmers practice slicing the whole length of risers except on stony risers. Farmers perceive that benefit of keeping natural grasses on terrace riser is less than slicing them from the riser. The soil erosion depends upon the height of the riser sliced. The more the slicing height, more is the erosion and viceversa. Farmers believe that cutting the grass foliage periodically and partial slicing (low height of riser) may be good techniques to keep grasses on terrace risers and edges without inducing soil loss and insect pest problem. But it has not been practiced yet in the study area because farmers do not want to take risk of insect pest problem. Farmers have good experiences that the problems of insects/pests are totally (>90%) controlled in improved varieties of grasses but mice are the problems in case of Napier (Pennisetum purpureum) on dry sites.

Stylo and Molasses are most effective in armouring the slope against surface erosion from both runoff and rain splash due to their dense surface cover, low canopy and small leaves. Amliso and Napier are most effective in reinforcing the soil by providing a network of strong roots that increases the soil’s resistance to shear. Amliso can moderately support the soil mass by its strong and long fibrous roots. Amliso (Thaisanolaena maxima) is excellent in interception, storage and leaf drip because of its great height (up to 4.9 m), foliage lateral spread (up to 5.14 m, and large clumping characteristics. However, infiltration is low due to its strong fibrous roots catching the soil firmly leaving few pores in the soil. Mat formation is excellent in Napier and Molasses due to their fine fibrous roots spreading few centimetres below the ground surface.

This study reveals that spacing depends on the root lateral spread of vegetation. Accordingly, spacing is highest in Amliso and lowest in Molasses. The quantity of planting material required for cultivation depends upon the spacing and pattern of cultivation of grasses. For the triangular fashion of cultivation, Molasses needs more planting material than Napier, Amliso and Stylo. Amliso is most effective in terms of quantity of planting material needed. The quantity of planting material has direct bearing on cost of cultivation of improved grass varieties.

It is recommended that terrace risers should not be sliced more than 1 m above the ground surface to reduce the erosion risk. A trial and demonstration plot should be established to show farmers the effects of partial slicing (only up to 1m) and periodic foliage cutting of grasses on terrace risers because farmers agree that this technique may be best option to grow grasses on terrace risers. To prevent or reduce the shading effect of grasses on cereal crops on terraces, their foliage should be cut periodically as follows: Napier: 15-25 cm (6 to 10 inches) above the ground; Molasses: 8-10 cm above the ground; Amliso: 20-30 cm above the ground. Spacing for Napier, Stylo, Molasses and Amliso should be kept 90 cm, 130 cm, 45 cm, and 2.4 meter in plane area respectively and for slopes it should be 67.5 cm, 97.5 cm, 33.75 cm and 1.8 m respectively.

Trainings on improved grass cultivation and management should be provided to the farmers. Farmers are very much interested to cultivate the improved grasses on marginal land, but they can hardly obtain planting materials (seeds/seedlings/stem-cuttings). So a local community nursery should be established through community development groups (CDGs). NARMSAP and DSCO, Lamjung should design and implement with coordination and cooperation with each other.