Impact of Forage Fertilization with Urea and Composted Cattle Manure on Soil Fertility in Sandy Soils of South-Central Vietnam

Keenan C Mcroberts,Tran Thanh Hai,David Parsons,Nguyen Xuan Ba,Debbie J R Cherney,Nguyen Hai Quan,Quirine M Ketterings,Charles F Nicholson

doi:10.1155/2016/4709024

Abstract

Increased production in smallholder beef systems requires improved forage management. Our objective was to evaluate the effects of composted cattle manure and mineral nitrogen (urea) application on soil fertility and partial nutrient balances in plots established toBrachiariacv. Mulato II in south-central coastal Vietnam from 2010 to 2013. A randomized complete block design was implemented on six farms (blocks), with five rates of composted cattle manure (0, 4, 8, 12, and 24 Mg DM/ha per yr) and three urea rates (0, 60, and 120 kg N/ha per yr) in a factorial design. Soil was analyzed before and after the experiment. Compost increased soil pH, organic matter, Ca, Mg, and Mn. The effect of compost and urea applications on postexperiment soil fertility depended on preexperiment soil fertility for K, P, S, Mg, Zn, Mn, Cu, and organic matter, suggesting that the ability to maintain soil fertility depends on the interaction between soil organic and inorganic amendments and existing soil fertility. Highest farm yields were also achieved on farms with higher preexperiment soil fertility levels. Negative partial nutrient balances for N, P, and K suggest that yields will not be sustainable over time even for the highest fertilization inputs used in this experiment.

Highlights

Smallholder crop-livestock farms (≤5 head of cattle/household) in south-central coastal Vietnam contribute to beef supply for urban areas [1]
Preexperiment farm soil fertility levels were consistent with yield differences observed in the experiment
Significant mean difference (Bonferroni correction) was detected only in soil Na for compost applied at 12 Mg DM/ha per yr without urea, which was higher after the experiment (Table 8)

Summary

Introduction

Smallholder crop-livestock farms (≤5 head of cattle/household) in south-central coastal Vietnam contribute to beef supply for urban areas [1]. Semi-intensive (grazing and stall feeding) and extensive (grazing of communal land) cattle management systems are dominant in the region. Progressive farmers have transitioned toward semi-intensive management of backyard plots to increase animal productivity (daily gain) using supplementary forages (native grasses and legumes and cultivated improved forages) and concentrates and reducing energy expenditures incurred from walking to open grazing areas. Key to this transition is cultivation of high-yielding, high nutritive value forages that are well adapted to local climatic and soil conditions [1,2,3,4].

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Methods

Results

Discussion

Conclusion