Impact of rice cultivation on evapotranspiration in small seasonal wetlands of north-central Namibia

Abstract

This paper aims to evaluate the effect of mixed-cropping of rice and upland crops on evapotranspiration (ET) in a small seasonal wetland in the north-central Namibia. Meteorological observations were conducted in the experimental sloped field, which simulated the cultivation of both rice in a wetland environment and upland crops in the surrounding rain-fed area, and included a reference wetland with natural vegetation. During cultivation, ET from the rice field was similar to that from the wetland. However, during the dry period ET was remarkably reduced in the post-harvest field, while continuous ET occurred in the natural wetland even after surface water had dried up. The response of surface conductance to meteorological variables was investigated by means of the Jarvis-Stewart conductance model. During cultivation, surface conductance of the rice field and the wetland had a distinct stress response compared with that of the rain-fed crop field. During the dry period, surface conductance of the wetland site, in which the surface water dried-up, still responded to the meteorological conditions in contrast to those of the post-harvest field with plowed bare soil.

Effects of Cultivation Management on Pearl Millet Yield and Growth Differed with Rainfall Conditions in a Seasonal Wetland of Sub-Saharan Africa

“…The experiments were conducted on the lower part of a slope in the field to simulate cultivation in small, seasonal wetlands. An experimental field was set up, which was 80 m × 160 m in size, with an artificial slope of 1/80 [24,25]. Weather data were obtained from the Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL) website (http://www.sasscalweathernet.org/weatherstat_monthly_we.php, accessed date: 10 March 2021).…”

Growth and Productivity Assessment of Short-Duration Rice (Oryza sativa L. and Upland NERICA) Genotypes in Semiarid North-Central Namibia

“…e advent of upland NERICA rice [16] has created an opportunity to extend rice production into semiarid, Sub-Saharan agroecosystems [6,[17][18][19]. Recent studies in northern Namibia have demonstrated that rice can be cultivated in the local seasonal wetlands [9,10,20], without modifying the water environment in the system [21][22][23]. Currently, rice farming in the country was done by few producers; thus, the wetlands are traditionally used for seasonal livestock grazing and fishing [12,24], despite the high demand for homegrown rice [6].…”

“…Moreover, since the wetlands are seasonal, most of the water is eventually lost through evaporation and by deep percolation. Increasing rice cultivation in the local wetland ecosystems has the potential to offer new rice-based foodstuffs and a new cropping land area, complementary to the existing arable land used for the production of traditional dryland crops, while simultaneously conserving the local water environment [23].…”

Consolidation and Deformation Characteristics of Soft Rock Foundation in Hydrological Wetland Environment

“…The response and feedback mechanism of hydrological wetland ecosystem under the influence of global change and human activities is the focus and frontier issue of common concern in the international community (Guo, 2018). Consolidation and deformation characteristics of soft rock foundation in hydrological wetland environment are affected by many factors, such as physical and mechanical properties of soft rock and soil, sludge thickness of hydrological wetland, loading capacity, loading mode and field environment (Xu et al, 2017;Kotani et al, 2017). In the hydrological wetland area, in order to carry out the construction of soft rock foundation smoothly, cofferdams are built on both sides of most sections before foundation treatment, and counter-pressure barriers are built between cofferdams and roads.…”