Effect of cattle manure application method on forage production of Panicum maximum in central coastal Vietnam

Forage production in smallholder crop-livestock farming communities of South Central Coastal (SCC) Vietnam occurs largely on sandy soils which are low in key macro-nutrients and organic carbon. The benefit of applying cattle manure to the soil is not clear. Further, the amount of manure applied, and the method of application to the soil is highly variable. Greater knowledge on the relative benefits of manure incorporation versus surface application would assist smallholder farmers in managing the use of manure in growing forages in the SCC region. n experiment was conducted in Binh Dinh province on the effect of manure application on growth of Panicum maximum cv. TD58. The treatments were four manure application rates (0, 10, 20 and 30 t DM/ha/yr on a dry matter basis) and two methods of application (surface application and incorporation to 5-10 cm) in a randomized complete block design with 4 replicates. Manure was applied in a double application at planting, then following every second harvest.

Method of application had no effect on the forage yield. There was a significant increase in total yield when manure was applied at rates of up to 20 t DM/ha/yr, but no significant additional response at 30 t/DM/ha/yr. The yields were 17.4 t DM/ha, 19.3 t DM/ha, 21.5 t DM/ha and 22.5 t DM/ha for 0, 10, 20, and 30 t DM/ha/yr of manure respectively. In the wet season the CP in the forage decreased with increasing manure application. Manure rate and method of application increased soil fertility parameters. Farmers must balance the soil fertility and production benefits with the opportunity to sell manure for an immediate return.