Measuring soil evaporation from a cropped land in the semi-arid Makanya catchment, Northern Tanzania: Methods and challenges

Abstract

Estimating soil water loss from cropped land is vital for sustainable management of water resources in semi-arid and hot regions. Soil evaporation (Es) is an important process in these regions but hard to quantify. The study aimed at quantifying Es in maize field under three treatments using microlysimeters (MLs). It also aims to identify sources of challenges in the method. The treatments were; flat cultivation with mulching (FCM), without mulches (FC) and double digging (DD, manual tillage practice), were replicated trice. In each plot, two micro-lysimeters were installed, one containing soil samples to measure soil evaporation and an empty one to measure throughfall (Ʈr) under the maize canopy. The 24-hr soil samples weight change and throughfall records were used to estimate soil evaporation for each plot. The estimated mean daily soil evaporation was 3.4 mm/day in FC, 2.1 mm/day in FCM and 3.0 mm/day for DD. There was a challenge in the method during the rainfall period which lead to both negative and high Es values during rainfall period. Less throughfall from empty MLs than in soil containing MLs caused the negative Es and the opposite was true for higher Es during rainy period. We urge the method to be improved by measuring throughfall simultaneously with soil weight changes immediately after rainfall events and minimize random errors by using many MLs. To have more results on reducing water losses while increasing available water for crop growth in this water scarce environment, we suggest FCM to be combined with DD treatment.

Fractal Characteristics of Natural Fiber-Reinforced Soil in Arid Climate Due to Cracking

“…Cabangon and Tuong [38] used straw mulch to cover soil cracks, which not only helped to retain moisture in the soil, but also limited the development of cracks. Nyabwisho et al [39] applied three different types of treatments in a semi-arid area of Northern Tanzania in East Africa to determine the amount of soil evaluation; among which, one is mulching. They used micro lysimeters to quantify soil evaporation and found that with mulching, soil evaporation is reduced by 28%.…”

The Stem Sap Flow and Water Sources for Tamarix ramosissima in an Artificial Shelterbelt With a Deep Groundwater Table in Northwest China

“…Williams et al (2004) illustrated that 95% of precipitation that reaches dryland ecosystems is lost through evapotranspiration and transpiration accounts for about 64% of total evapotranspiration globally (Good et al, 2015). Evapotranspiration is usually studied by using methods such as lysimeter measurements, the Bowen ratio, and eddy covariance approaches (Cassiani et al, 2015;Kucera et al, 2017;Jin et al, 2018;Nyabwisho et al, 2020). All of these methods can provide important information about ecosystem responses to environmental variability, but none of these approaches can be used to accurately evaluate the water consumption of individual plants.…”