Effects of Ridge Tillage and Straw Returning on Runoff and Soil Loss under Simulated Rainfall in the Mollisol Region of Northeast China

Ridge tillage and straw returning are tillage practices widely used in the Chinese Mollisol region. However, the effects of ridge tillage combined with straw returning on runoff and soil loss control are still unclear. The objective of this study was to compare the effects of ridge tillage practices (contour ridge (CR)) and longitudinal ridge (LR), straw returning practices (straw on the furrow surface (SS)) and straw below the furrow (SB)), and their interactions on the runoff and soil loss by using simulated rainfall experiment. Two rainfall intensities (45 and 60 mm h−1) were applied to six combinations of ridge tillage and straw returning (contour ridge treatment, contour ridge with straw on the furrow surface treatment, contour ridge with straw below the furrow treatment, longitudinal ridge treatment, longitudinal ridge with straw on the furrow surface treatment, and longitudinal ridge with straw below the furrow treatment) on a 5° slope. The results showed that the phenomenon of ridge failure was common in the treatments with contour ridge. The average runoff rate and soil loss rate after ridge failure for treatments with contour ridge were separated 2.8 and 3.5 times greater than those of before failure at 60 mm h−1. However, the corresponding values were only 68.6% and 43.3% of the average value of longitudinal ridge treatment and longitudinal ridge with straw below the furrow treatment at 60 mm h−1. The water storage capacities of treatments with contour ridge remained constant when the rainfall intensity varied. The water storage capacities of contour ridge with straw on and below the furrow treatments were separate 3.0 and 1.0 mm less than that of contour ridge. However, longitudinal ridge with straw on the furrow surface treatment increased the runoff rate by 7.4% but reduced the soil loss rate by 72.6% when compared with longitudinal ridge treatment and longitudinal ridge with straw below the furrow treatment under the two rainfall intensities. Longitudinal with straw on the furrow surface treatment was more conducive to the stability of ridges, and there was no significant difference in total soil loss between longitudinal ridge with straw on the furrow surface treatment and treatments with contour ridge. This study was based on simulated rainfall conditions, and its adaptability under long-term positioning monitor in the field should be added in future.

Experimental Study of Runoff and Sediment Yield Affected by Ridge Direction and Width of Sloping Farmland

Water and soil losses from sloping farmlands potentially contribute to water eutrophication and land degradation. However, few studies explored the combined effects of ridge direction and ridge width on surface runoff and soil losses of sloping farmlands. Twenty-seven experimental plots (8 m long and 4 m wide) with nine treatments (three ridge direction: cross ridge, longitudinal ridge, and oblique ridge; and three ridge width: 40, 60, and 80 cm) were adopted under natural rainfall conditions for two years in the Luanhe River Basin of China. Results indicated that ridge direction had significant effects on runoff and sediment yield (p < 0.05). The ridge width had no significant effect on runoff and sediment yield. No significant interaction effect was found between ridge direction and width on runoff and sediment yield of the sloping farmland based on statistical analyses. Compared with cross-ridge (CR) tillage and oblique-ridge (OR) tillage, longitudinal-ridge (LR) tillage significantly decreased runoff by 78.9% and 64.9% and soil losses by 88.2 and 83.5%, respectively (p < 0.05). The effects of ridge directions on runoff and sediment yield were related to rainfall grade. When the rainfall grade reached rainstorm, the runoff yield under CR, LR, and SR had significant differences (p < 0.05). The runoff under LR and OR treatment was 5.16 and 3.3 times, respectively, of that under CR. When the rainfall level was heavy rain or rainstorm, the sediment yield under LR was significantly greater than that under CR. The sediment yield was 13.45 times of that under CR. Cross-ridge tillage with a ridge width of 40 cm is an optimally effective measure of soil and water conservation on sloping farmland in arid and semiarid regions of China.

Geomorphic and sedimentary characteristics of ancient Dora Kamiyama rockslide in Tibet Plateau - implications of dynamic process and frictional heating

<p>The mechanisms of high-speed and long-runout landslides are mainly reflected in the geomorphological morphology and internal sedimentology of the deposits. The geomorphic and sedimentary characteristics of ancient Dora Kamiyama rockslide in Tibet Plateau was discussed based on field investigation and multidisciplinary tests. The landslide area is divided into three zones: the source area (I), the translation area (II), and the accumulation area (III). Geomorphic features include toreva block, the levee, the transverse ridge, the longitudinal ridge, the hummock and the ridge confined by troughs and the carapace composed of giant blocks were analysed,which are considered as indicators of the dynamic process of the landslide during transport. 3 stages of the rockslide dynamic motion were proposed, including extensional, compressional and radial motions, respectively. Sedimentary features of facies in the rockslide was revealed, including carapace facies, blocky facies, fragmented facies, shear zones, and basal mixed zones, the mineral change process of the rockslide during the movement process and the temperature change of the sliding surface can be obtained based on analyzing the minerals change near the shear zone. The temperature field of the landslide and its movement process can be reconstructed through the temperature change of the shear zone. The results show that frictional heating was generated during complex dynamics interactions. The friction temperature generated by sliding near the fragmented facies was about 870–1470 °C. Based on sedimentary evidence, the dynamic evolution of the rockslide in response to temperature changes were reconstructed based on frictional thermal analysis.</p>

Nutrient and Stoichiometric Characteristics of Aggregates in a Sloping Farmland Area under Different Tillage Practices

Sloping farmland is prevalent in hilly red soil areas of South China. Improper tillage patterns induce decreased soil organic matter, soil aggregate breakdown, and nutrient imbalance, thereby restricting crop production. However, the stoichiometric characteristics could reflect the nutrient availability which was mostly studied on bulk soil. The stoichiometric characteristics of soil aggregates with multiple functions in farmlands has rarely been studied. The study was to reveal the impact of tillage patterns on the size distribution, nutrient levels, and stoichiometric ratios of soil aggregates after 20 years’ cultivation. Soil samples of 0–20 cm and 20–40 cm from five tillage patterns, bare-land control (BL), longitudinal-ridge tillage (LR), conventional tillage + straw mulching (CS), cross-ridge tillage (CR), and longitudinal-ridge tillage + hedgerows (LH) were collected. The elemental content (C, N and P) and soil aggregate size distribution were determined, and the stoichiometric ratios were subsequently calculated. Through our analysis and study, it was found that the nutrient content of >2 mm soil aggregates in all plots was the highest. In the hedgerow plots, >2 mm water-stable soil aggregate content was increased. Therefore, LH plots have the highest content of organic matter and nutrients. After 20 years of cultivation, stoichiometric ratio of each plot showed different changes on soil aggregates at different levels. the C:N, C:P, and N:P ratios are lower than the national average of cultivated land. Among of them, the stoichiometric ratio in the LH plot is closer to the mean and showed better water-stable aggregate enhancement. Therefore, longitudinal-ridge tillage + hedgerows can be recommended as a cultivation measure. This study provides a reference for determining appropriate tillage measures, balancing nutrient ratios, and implementing rational fertilization.

The value of a complex unit for the simultaneous use of a transverse surface and a longitudinal ridge when irrigating cotton

The article provides data on the development of a complex Palodelatel unit without damaging growing plants, the simultaneous rate of a transverse surface and a longitudinal ridge in saline, sloping uneven soils in the Bukhara region, also taking into account the slope and unevenness of the soil relief, in a scientifically based form it is stated about the uniform provision of irrigation water and reduction of manual labor, working time, duration and distance between irrigation days, saving spent irrigation water and elimination of salt spots and reducing the cost of irrigation water by 25%, irrigation duration by 1.5-2 days, crop addition by 5-4.2 c / ha.

Two newly identified cheiracanthid acanthodians from the Mey Flagstone Formation (Givetian, Middle Devonian) of the Orcadian Basin, Scotland

Articulated cheiracanthid acanthodians are relatively rare above the Dickosteus thrieplandi biostratigraphic zone in the Orcadian Basin, with Cheiracanthus peachi den Blaauwen, Newman & Burrow the only species identified to date. Here we describe two other taxa Fallodentus davidsoni nov. gen. et sp. and Markacanthus costulatus Valiukevičius from the Mey Flagstone Formation. F. davidsoni occurs at the base of the formation, in the Osteolepis panderi biostratigraphic zone, and is readily identified by its robust fin spines which have a wide longitudinal ridge on each side below the groove separating the leading edge from the side of the spine. The taxon is most similar to Homalacanthus concinnus (Whiteaves) from the younger (Frasnian) Escuminac Formation in Quebec, Canada. The unique specimen of Markacanthus costulatus is from the top of the Mey Flagstone Formation. This taxon was previously only known from isolated scales from the upper Narva and Aruküla Regional Stages of the east Baltic region. The dorsoventral preservation of the head region in the F. davidsoni specimens reveals clearly the position of the ceratohyal cartilages in a cheiracanthid, as well as showing for the first time that there is a basihyal cartilage anterior to the ceratohyals.

Epipogium taiwanense, a detail morphological description and additional new record to mainland China

Epipogium taiwanense, is published in the book of Illustrated Flora of Taiwan in 2018. However, here only the specimen and simply descriptions were existed on which the protologue was based. Plant and flowers characteristics were not described in enough detail in the original description. Fortunately, it was rediscovered from Yunnan and Sichuan Province, China. It is morphological similar to E. aphyllum, but it can be easily distinguished from the latter by having large size flower bract (2.0 × 1.0 cm, significantly longer than pedicel and ovary), epichile of labellum concave with 1 longitudinal ridge on mid-lobe and the spur strongly recurve in the apex connecting with bottom of mid-lobe. A preliminary risk-of-ex­tinction assessment, according to the IUCN Red List Categories and Criteria, is given for the newly recorded species.

Glycera sheikhmujibi n. sp. (Annelida: Polychaeta: Glyceridae): A New Species of Glyceridae from the Saltmarsh of Bangladesh

A new species of glycerid polychaete, Glycera sheikhmujibi, is described from the saltmarsh on the central coast of Bangladesh. The species is identified based on morphological characteristics using both a light microscope and scanning electron microscope (SEM). The species is characterized by the presence of three distinct types of proboscideal papillae: type 1 papillae (conical with three transverse ridges), type 2 (conical with a straight, median, longitudinal ridge), and type 3 (round, shorter, and broader, with a straight, median, longitudinal ridge). It has a Y-shaped aileron with gently incised triangular base, almost equal-size digitiform noto- and neuropodial lobes in the mid-body, and long ventral cirri at the posterior end. The new species is compared with its related species, previously described from the Bay of Bengal region. A key to all these species is provided.

Tazarcus, a new phylogenetically unplaced genus of two flightless weevils with metapleural ridge from the Eastern Arc Mountains, Tanzania (Coleoptera: Curculionidae: Molytinae)

This paper reports new flightless forest litter weevils discovered in Tanzania. They are classified into two species of the genus Tazarcus gen. nov.: T. aeaea sp. nov. (the type species; from South Pare and West Usambara) and T. ogygia sp. nov. (Rubeho). Both new species inhabit the archipelago-type Eastern Arc Mountain rainforests renowned for the high diversity of their biota. Adults of Tazarcus are recognizable by their relatively small size (length of pronotum and elytra in dorsal view 2.0–3.4 mm), the short and straight rostrum covered dorsally with dense velvety pilosity, an antennal funicle with seven segments, a prosternal canal, procoxae separated, a lack of hind wings and effaced elytral shoulders. Remarkably, adults of Tazarcus possess a short longitudinal ridge on each metapleuron, which bears a line of serration likely homologous to sclerolepidia. A phylogenetic analysis of 72 terminals and 3134 aligned positions from one mitochondrial and two nuclear ribosomal fragments corroborated the monophyly of the new genus, of both new species and of all three sampled populations but did not identify the sister group of Tazarcus. Three other weevil taxa with adults possessing a similarly shaped metapleural ridge (the African Thrombosternus Marshall and Allocycloteres Voss and an unidentified species of Molytinae from Madagascar) did not cluster with Tazarcus, suggesting multiple origins of this structure. Tazarcus is taxonomically classified as incertae sedis in a non-monophyletic subfamily “Molytinae”. Images and DNA sequences of all 72 herein analysed specimens are available online at dx.doi.org/10.5883/DS-VGDS011.