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Browsing Doktoraty (WNGiG) by Author "Ceglarek, Jakub"
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Item Roczna zmienność areału gleb ornych nie pokrytych roślinnością w skali globalnej(2019) Ceglarek, Jakub; Cierniewski, Jerzy. PromotorArable land around the world has a 12% share of the global land area. This thesis was created as a part of a project aimed at estimation of shortwave radiation reflected from those surfaces according to various scenarios based on the farming methods. This thesis was created as a part of a project aimed at estimation of shortwave radiation reflected from those surfaces according to various scenarios based on the farming methods. Its key element was the estimation of the bare soil area, defined for its spectral properties, as the area of arable land not covered by vegetation on more than 15% on its surface. In conventional agriculture, during the period immediately following the planting of crops, the soil stays bare until the newly planted crops reach defined above share of surface cover. This work focuses on estimating the periods of bare soil that occur after the planting of 13 major crops at the global scale; those selected crops are wheat, maize, barley, sorghum, soybeans, millet, cotton, rapeseed, groundnuts, potato, cassava, rye, and sugar beet. The supplementary objective of the study was to determine which soil groupings, and in what proportions, were bare during those periods. Arable land, divided into extensive agricultural regions located on six continents, was analyzed. The estimation of bare soil acreage was performed based on publicly available spatial datasets including the distribution of arable land in the world, crop calendars containing planting dates and the geographic distribution of crops. The arable land in the world was first divided into agricultural regions inspired by the division proposed by United States Department of Agriculture. For each region, average daily temperatures were used to predict plant growth stages. For each crop within a region, the planting date was used as the beginning of the bare soil period, which ended when it reached a stage where at least 15% of the surface was covered by vegetation. The aggregated periods concerning every crop within any given region resulted in an annual variation of bare soil area. The acreages of soil grouping used in agriculture for any region were then extracted based on the location of arable land and the region’s boundaries.The global annual variation of bare soil area shows that the maximum level occurs around the 140th day of the year (DOY) (middle of May), influenced primarily by the planting of crops occurring in the northern hemisphere. Up to 1.5 million km2of soil surface stays bare at that time. Centered on that maximum is a period of bare soil lasting for almost four months, between the 92nd DOY and the 200th DOY (early April and end of July), when two lesser maxima were observed, of around 900,000 and 700,000 km2, respectively. The equivalent of that period, resulting from planting in the southern hemisphere, starts around the 330th DOY (middle of November) and lasts for about a month, reaching almost 400,000 km2. The other distinguishable episode of bare soil in the southern hemisphere was noted between the 15th and the 25th DOY (second half of January) when its area reached 100,000 km2. Asia is the super region with by far the largest area of arable land and consequently, it sports the highest acreage of bare soil. During the aforementioned maximum in the northern hemisphere occurring around the 140th DOY, the Asian super region contributes around 700,000 km2 of bare soil, which is almost half of the bare soil area for the whole northern hemisphere at that time, with Lithosols, Cambisols, and Gleysols being the major soil groupings that stay bare. In Europe, two distinct periods of bare soil were found; during the first, starting around the 40th DOY (middle of February) and lasting until the 150th DOY (end of May), the steady increase of the bare soil area lasts until the 140th DOY (middle of May) when it reaches almost 500,000 km2, after which a rapid decline was observed. The second, manifesting two and a half months later, lasts between around the 230th and the 290th DOY (middle of August to middle of October), and exceeds 100,000 km2. Chernozems, Cambisols, and Luvisols are dominant soil groupings on arable land in Europe. Similar trends, related to the European bare soil areas, were found in the North American super region, where a period of maximum bare soil area occurs in late spring, and a second period, characterized by a much smaller area, follows the main one three months later. The maxima coincide with the aforementioned ones in Asia and Europe, reaching 300,000 km2 of bare soil around the 140th DOY. Similar to Europe, the second period sports a much smaller bare soil area, short of 30,000 km2. The dominant soil groupings in agricultural use in North America are Kastanozems, Luvisols, and Chernozems. Africa is a super region whose area is divided between both northern and southern hemispheres, which shows in the annual variation of its bare soil area. Three distinct periods were found there, the major one around the middle of a year lasted for about two and a half months, between the 167th and the 230th DOY (middle of June to middle of August) with the bare soil area being up to almost 400,000 km2. The other peak occurs about a month and a half earlier, between the 95th and the 115th DOY (roughly the month of April) and is characterized by a bare soil area exceeding 120,000 km2. The last notable episode of bare soil in Africa manifests itself between the 317th DOY and the 10th day of the following year (middle of November to the middle of January), with the area of soil uncovered by vegetation reaching almost 100,000 km2. Luvisols together with Arenosols, followed by Vertisols, are the most extensively farmed soil groupings in Africa. The majority of arable land in the southern hemisphere is found in the South American super region, which is reflected in the annual variation of bare soil area, which is similar to that of the whole southern hemisphere. The maximum lasts for around two weeks, between the 330th and the 345th DOY (end of November to the middle of December), when almost 500,000 km2 of arable soil is bare. A secondary peak was observed between the 15th and the 30th DOY (second half of January), sporting around 100,000 km2 of bare soil area. Ferrasols is the most commonly farmed soil grouping in the region, followed by Phaozems and Luvisols. In Oceania, the maximum area of bare soil slightly exceeds 25,000 km2 for about two weeks in the first half of June, followed by a rapid decline. A secondary period is characterized by a longer duration but the smaller area, lasting between the 313th and the 14th DOY (middle of November to middle of January) with about 5,000 km2 of arable land which is not covered by vegetation at that time. Luvisols are the dominant soil grouping under cultivation in Oceania, followed by Planosols, Solonetz, and Vertisols. The obtained variations of bare soil areas together with the corresponding share of soil groupings for all regions were used in other work in order to estimate the amount of shortwave radiation reflected from those surfaces according to various scenarios based on the farming methods.