Effect of Soil Properties on Tree Distribution across an Agricultural Landscape on a Tropical Mountain, Tanzania

Abstract. Globally, tropical forest soils represent the second largest source of N2O and NO. However, there is still considerable uncertainty on the spatial variability and soil properties controlling N trace gas emission. To investigate how soil properties affect N2O and NO emission, we carried out an incubation experiment with soils from 31 locations in the Nyungwe tropical mountain forest in southwestern Rwanda. All soils were incubated at three different moisture levels (50, 70 and 90% water filled pore space (WFPS)) at 17 °C. Nitrous oxide emission varied between 4.5 and 400 μg N m−2 h−1, while NO emission varied from 6.6 to 265 μg N m−2 h−1. Mean N2O emission at different moisture levels was 46.5 ± 11.1 (50% WFPS), 71.7 ± 11.5 (70% WFPS) and 98.8 ± 16.4 (90% WFPS) μg N m−2 h−1, while mean NO emission was 69.3 ± 9.3 (50% WFPS), 47.1 ± 5.8 (70% WFPS) and 36.1 ± 4.2 (90% WFPS) μg N m−2 h−1. The latter suggests that climate (i.e. dry vs. wet season) controls N2O and NO emissions. Positive correlations with soil carbon and nitrogen indicate a biological control over N2O and NO production. But interestingly N2O and NO emissions also showed a negative correlation (only N2O) with soil pH and a positive correlation with free iron. The latter suggest that chemo-denitrification might, at least for N2O, be an important production pathway. In conclusion improved understanding and process based modeling of N trace gas emission from tropical forests will not only benefit from better spatial explicit trace gas emission and basic soil property monitoring, but also by differentiating between biological and chemical pathways for N trace gas formation.

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Variability of Soil Properties in Eroded Agricultural Landscape

Journal of Ecological Engineering ◽

10.12911/22998993/113154 ◽

2020 ◽

Vol 21 (1) ◽

pp. 72-80

Author(s):

Agnieszka Wysocka-Czubaszek

Keyword(s):

Soil Properties ◽

Agricultural Landscape

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Spatial Assessment of Selected Soil Properties within an Industrial Poultry Production Site

Air Soil and Water Research ◽

10.4137/aswr.s9268 ◽

2012 ◽

Vol 5 ◽

pp. ASWR.S9268 ◽

Cited By ~ 4

Author(s):

Raymon S. Shange ◽

Ramble O. Ankumah ◽

Leonard Githinji ◽

Robert Zabawa

Keyword(s):

Soil Properties ◽

Principal Components ◽

Agricultural Landscape ◽

Environmental Problem ◽

Production Systems ◽

Soil Surface ◽

Poultry Production ◽

Biochemical Activity ◽

Surface Maps ◽

The Us

Waste resulting from industrial poultry production systems is becoming an increasingly significant environmental problem in the US, threatening both soil and water quality. The goal of this study was to assess the spatial variability and interactions of selected soil properties (physical, chemical, and biochemical), viz., particle size, pH, enzymatic activity, Soil Organic Carbon (SOC), and Total Nitrogen (TN), across an agricultural landscape used for industrial poultry production. The measured soil properties were separated according to biochemical constituents and soil texture based on the first two principal components, accounting for approximately 60% of the variability across the site. These principal components were then used to generate soil surface maps, indicating areas of possible catalytic activity. Surface maps showed possible increases in biochemical activity around areas of stored poultry litter, suggesting the utility of these methods in determining changes to soil management.

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Greenhouse Gas Emissions from Forest Soils Reduced by Straw Biochar and Nitrapyrin Applications

Land ◽

10.3390/land10020189 ◽

2021 ◽

Vol 10 (2) ◽

pp. 189

Author(s):

Jinbiao Li ◽

Jin-Hyeob Kwak ◽

Scott X. Chang ◽

Xiaoqiang Gong ◽

Zhengfeng An ◽

...

Keyword(s):

Soil Properties ◽

Forest Soils ◽

Agricultural Landscape ◽

Microbial Biomass Carbon ◽

Ghg Emissions ◽

N2o Emissions ◽

Brassica Napus L ◽

Significant Interaction Effect ◽

Ch4 Uptake ◽

Cumulative Co2 Emissions

Forestlands are widely distributed in the dominantly agricultural landscape in western Canada, and they play important ecological functions; such forestlands (e.g., shelterbelts) accumulate soil organic matter and may receive a substantial amount of nitrogen in the form of surface and subsurface runoff from adjacent croplands and become a significant source of emissions of greenhouse gases (GHGs) such as CO2, N2O, and CH4. Biochar and nitrapyrin applications could potentially mitigate GHG emissions, but their co-application in forest soils has not been studied. We investigated the effect of the application of biochars produced at low (300 °C; BC300) and high temperatures (700 °C; BC700) using canola (Brassica napus L.) straw and the effect of their co-application with nitrapyrin on GHG emissions and soil properties in a 35-day laboratory incubation experiment using forest soils collected from five shelterbelt sites. Results showed no significant interaction effect of biochar and nitrapyrin on the global warming potential (GWP) of the GHG emissions, and the GWP was 15.8% lower in the soil with nitrapyrin than without nitrapyrin application treatments. The GWP was significantly enhanced by BC300 addition due to a 26.9% and 627.1% increase in cumulative CO2 and N2O emissions, respectively, over the 35-day incubation. The GWP significantly decreased by BC700 addition due to a 27.1% decrease in cumulative CO2 emissions. However, biochar addition did not affect CH4 emissions, while nitrapyrin decreased CH4 uptake by 50.5%. With BC300 addition, soil-dissolved organic carbon and microbial biomass carbon increased by 26.5% and 33.9%, respectively, as compared to no biochar addition (CK). Soil pH increased by 0.16 and 0.37 units after the addition of BC300 and BC700, respectively. Overall, the effect of biochar and nitrapyrin was independent in mitigating GHG emissions and was related to the type of biochar applied and changes in soil properties.

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