Effects of cultivating different crops on soil erosion of slope farmland

The soil nutrient content, particle size composition, crop yield and erosion resistance were studied considering the slope farmland with different slope sizes and different crops as the research object. The results showed that the available phosphorus content was higher under the wheat planting mode. Rape planting was conducive to the accumulation of organic matter, total nitrogen and available potassium, and nutrient accumulation was more obvious when treated at 5° slope. The soil texture was sandy loam under the wheat planting mode. After rapeseed planting, the soil texture began to change to silt loam. The crop yield was the highest under different planting modes at 5°. Rapeseed was found to increase the soil erosion resistance of sloping farmland compared with wheat, and the greater was the slope, the stronger the erosion resistance. Bangladesh J. Bot. 50(3): 925-932, 2021 (September) Special

The Influence of Mechanical Composition and Mineral Composition of Calcareous Soil on Slope Farmland on Phosphorus Fixation

Soil erosion on slope farmland causes the degradation of soil quality and eutrophication of water bodies due to the loss of phosphorus. In order to explore the influence of soil mechanical composition and mineral composition on phosphorus fixation, we selected calcareous soil on slope farmland in the Three Gorges Reservoir area as the research object and separated the samples on the basis of particle size. Next, we determined the content of different forms of phosphorus for each particle size, and then characterized and analyzed the mineral composition. The adsorption performance of each particle size was also studied. The results show that the calcareous soil on slope farmland has a high proportion of coarse fractions, and the carbonate minerals enriched in coarse fractions will fix a large amount of phosphorus and degrade soil quality. As slope farmland is prone to soil erosion, when the soil undergoes selective migration, the loss of fine fractions will increase the proportion of coarse fractions and aggravate soil quality degradation. Meanwhile, because of the large amount of phosphorus adsorbed by fine fractions, the available phosphorus is easily lost with fine fractions, leading to eutrophication of water bodies.

Spatial Structure Characteristics of Slope Farmland Quality in Plateau Mountain Area: A Case Study of Yunnan Province, China

As an important part of farmland, the slope farmland is widely distributed in the central and western plateau mountain region in China. It is necessary to scientifically evaluate the slope farmland quality (SFQ) and analyze the spatial structure characteristics of SFQ to ensure reasonable utilization and partition protection of slope farmland resources. This paper takes the typical plateau mountain region—Yunnan Province in China—as an example and systematically identifies the leading factors of SFQ. The sloping integrated fertility index (SIFI) is adopted to reflect the SFQ. The evaluation system is built to quantitatively evaluate the SFQ and the spatial structure characteristics of SFQ were analyzed by a geostatistical model, autocorrelation analysis and spatial cold–hot spot analysis. The results show that the SFQ indexes in Yunnan Province are between 0.36 and 0.81, with a mean of 0.59. The SFQ grade is based on sixth-class, fifth-class, seventh-class and fourth-class land. The SFQ indexes present a normal spatial distribution, and the Gaussian model fits well with the semi-variance function of the spatial distribution of SFQ indexes. Furthermore, the spatial distribution of SFQ indexes is moderately autocorrelated. The structural factors play a major role in the spatial heterogeneity of SFQ indexes, but the influence of random factors should not be ignored. The spatial distribution of SFQ grades has a significant spatial aggregation characteristic, and the types of local indicators of spatial association (LISA) are based on high–high (HH) aggregation and low–low (LL) aggregation. The cold spot and hot spot distributions of SFQ grades display the significant spatial difference. The hot spot area is mainly distributed in Central Yunnan and the Southern Fringe, while the cold spot area mainly distributes in the Northeastern Yunnan, Northwestern Yunnan and Southwestern Yunnan. This study could provide a scientific basis for SFQ management and ecological environment protection in the plateau mountain region.