In:
Experimental Agriculture, Cambridge University Press (CUP), Vol. 52, No. 4 ( 2016-10), p. 635-653
Abstract:
Soil Organic Carbon (SOC) is a major indicator of soil fertility in the tropics and underlies variability in crop response to mineral fertilizers. Critical SOC concentrations that interact positively with N fertilizer for optimal crop yield are less understood. A study was conducted on a Ferralsol in sub-humid Uganda to explore the critical range of SOC concentrations and associated fractions for optimal maize ( Zea mays L.) yield response to applied mineral N fertiliser. Maize grain yield response to N rates applied at 0, 25, 50 and 100 kg N ha −1 in 30 fields of low fertility (SOC 〈 1.2%), medium fertility (SOC = 1.2–1.7%) and high fertility (SOC 〉 1.7%) was assessed. Soil was physically fractionated into sand-sized (63–2000 µm), silt-sized (2–63 µm) and clay-sized ( 〈 2 µm) particles and SOC content determined. Low fertility fields ( 〈 1.2% SOC) resulted in the lowest response to N application. Fields with 〉 1.2% SOC registered the highest agronomic efficiency (AE) and grain yield. Non-linear regression models predicted critical SOC for optimal yields to be 2.204% at the 50 kg N ha −1 rate. Overall, models predicted 1.9–2.2% SOC as the critical concentration range for high yields. The critical range of SOC concentrations corresponded to 3.5–5.0 g kg −1 sand-sized C and 9–11 g kg −1 for clay-sized C.
Type of Medium:
Online Resource
ISSN:
0014-4797
,
1469-4441
DOI:
10.1017/S0014479715000307
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2016
detail.hit.zdb_id:
2016166-9
detail.hit.zdb_id:
426677-8
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