TITLE:
Greenhouse Gas Emissions from Intermittently Flooded (Dambo) Rice under Different Tillage Practices in Chiota Smallholder Farming Area of Zimbabwe
AUTHORS:
George Nyamadzawo, Menas Wuta, Ngonidzashe Chirinda, Lizzie Mujuru, Jeffrey Lynn Smith
KEYWORDS:
Greenhouse Gases; Smallholder Farming Sector; Rice; Seasonal Wetland (Dambo)
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.3 No.4A,
October
31,
2013
ABSTRACT: Agriculture is one of the biggest
sources of greenhouse gases. Rice production has been identified as one of the
major sources of greenhouse gases, especially methane. However, data on the
contributions of rice towards greenhouse gas emissions in tropical Africa are limited. In
Zimbabwe, as in most of Sub-Saharan Africa, there are very few studies that
have explored greenhouse
gas emissions from agricultural lands. This study
reports the first dataset on greenhouse gas emissions from intermittently
flooded rice paddies in Zimbabwe. The objective of this study was to quantify greenhouse gas emissions from dambo rice under different tillage treatments,
which were conventional tillage, no tillage, tied ridges, tied fallows,
and mulching. Average soil nitrous
oxide emissions were 5.9, 0.2, 5.4, 5.2 and 7.8
μg·m-2·hr-1 for tied fallows, conventional tillage, tied
ridges, mulching and no tillage respectively. Average methane emission was 0.35
mg·m-2·hr-1 and maximum as 1.62 mg·m-2·hr-1.
Average methane emissions for the different tillage systems were 0.20, 0.18,
0.45, 0.52 and 0.38 mg·m-2·hr-1 for tied fallows,
conventional tillage, tied ridges, mulching and no tillage respectively. Carbon
dioxide emissions were 98.1, 56.0, 69.9, 94.8 and 95.5 mg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. The estimated emissions per 150 day cropping
season were 1.4, 3.6 and 0.6 kg·ha-1 for methane, carbon dioxide and
nitrous oxide respectively. We concluded that
intermittently saturated dambo rice Paddys are a potential source of greenhouse
gases which is important to global greenhouse gas budgets,
thus, they deserve more careful study.