Assessment of soil erosion and climate variability on Kerio Valley Basin, Kenya

This study was aimed at assessing soil erosion, climate variation and how climate has affected both the agro climatic and agro-ological zones of Kerio Valley basin. The basin faces challenges especially soil loss, due to the massive degradation that takes place in Kerio valley. Due to the increase in rainfall recently experienced in the area, most of the top soil has been carried away leading to excessive degradation of the valley, causing soil loss in the basin and subsequent deposition of the sediments in Lake Kamnarok which is an oxbow lake posing it to the threat of extinction. All these aforementioned factors, i.e. soil erosion, climate variation and land degradation have contributed to reduction of water storage capacity of the Lake. The main objective of this study was to assess the effects of soil erosion, climate variation on the basin and climate effect on agro-climatic and agro-ecological zones of the basin. Agro-climatic zones show how climate variability shapes agricultural landscape of an area while agro-ological zones show how agriculture affects the ecology of the basin. This includes the reduction of the lake size that has led to the disruption of the ecology of Lake Kamnarok and its environs, the major implications being the lake size reduction as the lake is proved to be a home for reptiles especially crocodiles. All these factors were finally assessed to determine their effect on water reduction capacity of Lake Kamnarok. The results depicted that the major factors that have caused changes in the basin and the Lake include heavy rainfall that has resulted in soil erosion and subsequent land degradation. These factors have eventually affected the agroclimatic and agroecological zones of the basin. This study integrated the use of Geographic Information System (GIS) and Remote Sensing (RS) to assess the areas with massive degradation and to quantify the amount of soil loss using Revised Universal Soil Loss Equation (RUSLE) model. It was concluded that the main factor that caused the changes in the agroclimatic and the agroecological zones was soil erosion which was influenced by climatic factors, i.e. rainfall and temperature

Mapping Meaning : Critical Cartographies for Participatory Water Management in Taita Hills, Kenya

Participation of local people is often neglected in natural resource management, which leads to failure to understand the social aspects and historical construction of environmental problems. Participatory mapping can enhance the communication of local spatial knowledge for management processes and challenge the official maps and other spatial representations produced by state authorities and scientists. In this study, we analyze what kind of social meanings can be revealed through a multimethod participatory mapping process focusing on water resources in Taita Hills, Kenya. The participatory mapping clearly complicates the simplified image of the physical science mappings, typically depicting natural water supply, by addressing the impacts of contamination, inadequate infrastructure, poverty, distance to the sources, and restrictions in their uses on people's access to water. Moreover, this shared exercise is able to trigger discussion on issues that cannot always be localized but still contribute to place making. Local historical accounts reveal the social and political drivers of the current water-related problems, making explicit the political ecology dynamics in the area.Peer reviewe

Soil microbial communities influencing organic phosphorus mineralization in a coastal dune chronosequence in New Zealand

The Haast chronosequence in New Zealand is an ∼6500-year dune formation series, characterized by rapid podzol development, phosphorus (P) depletion and a decline in aboveground biomass. We examined bacterial and fungal community composition within mineral soil fractions using amplicon-based high-throughput sequencing (Illumina MiSeq). We targeted bacterial non-specific acid (class A, phoN/phoC) and alkaline (phoD) phosphomonoesterase genes and quantified specific genes and transcripts using real-time PCR. Soil bacterial diversity was greatest after 4000 years of ecosystem development and associated with an increased richness of phylotypes and a significant decline in previously dominant taxa (Firmicutes and Proteobacteria). Soil fungal communities transitioned from predominantly Basidiomycota to Ascomycota along the chronosequence and were most diverse in 290- to 392-year-old soils, coinciding with maximum tree basal area and organic P accumulation. The Bacteria:Fungi ratio decreased amid a competitive and interconnected soil community as determined by network analysis. Overall, soil microbial communities were associated with soil changes and declining P throughout pedogenesis and ecosystem succession. We identified an increased dependence on organic P mineralization, as found by the profiled acid phosphatase genes, soil acid phosphatase activity and function inference from predicted metagenomes (PICRUSt2)

Maize yield prediction and condition monitoring at the sub-county scale in Kenya: synthesis of remote sensing information and crop modeling

Abstract Agricultural production assessments are crucial for formulating strategies for closing yield gaps and enhancing production efficiencies. While in situ crop yield measurements can provide valuable and accurate information, such approaches are costly and lack scalability for large-scale assessments. Therefore, crop modeling and remote sensing (RS) technologies are essential for assessing crop conditions and predicting yields at larger scales. In this study, we combined RS and a crop growth model to assess phenology, evapotranspiration (ET), and yield dynamics at grid and sub-county scales in Kenya. We synthesized RS information from the Food and Agriculture Organization (FAO) Water Productivity Open-access portal (WaPOR) to retrieve sowing date information for driving the model simulations. The findings showed that grid-scale management information and progressive crop growth could be accurately derived, reducing the model output uncertainties. Performance assessment of the modeled phenology yielded satisfactory accuracies at the sub-county scale during two representative seasons. The agreement between the simulated ET and yield was improved with the combined RS-crop model approach relative to the crop model only, demonstrating the value of additional large-scale RS information. The proposed approach supports crop yield estimation in data-scarce environments and provides valuable insights for agricultural resource management enabling countermeasures, especially when shortages are perceived in advance, thus enhancing agricultural production

Correction to:Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities (Plant and Soil, (2018), 427, 1-2, (191-208), 10.1007/s11104-017-3391-x)

The article “Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities”, written by Timothy S George et al., was originally published with incorrect affiliation information for one of the co-authors, E. Klumpp

Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities

International audienceBackground The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction. Scope We asked a group of experts to consider the global issues associated with Po in the terrestrial environment, methodological strengths and weaknesses, benefits to be gained from understanding the Po cycle, and to set priorities for Po research. Conclusions We identified seven key opportunities for Po research including: the need for integrated, quality controlled and functionally based methodologies; assessment of stoichiometry with other elements in organic matter; understanding the dynamics of Po in natural and managed systems; the role of microorganisms in controlling Po cycles; the implications of nanoparticles in the environment and the need for better modelling and communication of the research. Each priority is discussed and a statement of intent for the Po research community is made that highlights there are key contributions to be made toward understanding biogeochemical cycles, dynamics and function of natural ecosystems and the management of agricultural systems

Correction to: Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities

Correction to: Plant Soil. https://doi.org/10.1007/s11104-017-3391-