Hyperspectral estimation of soil organic matter content using grey relational local regression model

PurposeThis study aims to improve the accuracy of hyperspectral estimation of soil organic matter content.Design/methodology/approachBased on the uncertainty in spectral estimation, 76 soil samples collected in Zhangqiu District, Jinan City, Shandong Province, were studied in this paper. First, the spectral transformation of the spectral data after denoising was carried out by means of 11 transformation methods such as reciprocal and square, and the estimation factor was selected according to the principle of maximum correlation. Secondly, the grey weighted distance was used to calculate the grey relational degree between the samples to be estimated and the known patterns, and the local linear regression estimation model of soil organic matter content was established by using the pattern samples closest to the samples to be identified. Thirdly, the models were optimized by gradually increasing the number of modeling samples and adjusting the decision coefficient, and a comprehensive index was constructed to determine the optimal predicted value. Finally, the determination coefficient and average relative error are used to evaluate the validity of the model.FindingsThe results show that the maximum correlation coefficient of the seven estimated factors selected is 0.82; the estimation results of 14 test samples are of high accuracy, among which the determination coefficient R2 = 0.924, and the average relative error is 6.608%.Practical implicationsStudies have shown that it is feasible and effective to estimate the content of soil organic matter by using grey correlation local linear regression model.Originality/valueThe paper succeeds in realizing both the soil organic matter hyperspectral grey relation estimating pattern based on the grey relational theory and the estimating pattern by using the local linear regression.

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Soil nitrogen supply of peat grasslands estimated by degree days and soil organic matter content

Nutrient Cycling in Agroecosystems ◽

10.1007/s10705-020-10071-z ◽

2020 ◽

Vol 117 (3) ◽

pp. 351-365

Author(s):

J. Pijlman ◽

G. Holshof ◽

W. van den Berg ◽

G. H. Ros ◽

J. W. Erisman ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Nitrogen ◽

Organic Matter Content ◽

Matter Content ◽

Nitrogen Supply ◽

Degree Days ◽

Soil Organic Matter Content ◽

Soil Nitrogen Supply

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Estimation of soil organic matter content based on CARS algorithm coupled with random forest

Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy ◽

10.1016/j.saa.2021.119823 ◽

2021 ◽

pp. 119823

Author(s):

Jinbao Liu ◽

Zhenyu Dong ◽

Junshi Xia ◽

Huanyuan Wang ◽

Tingting Meng ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Random Forest ◽

Organic Matter Content ◽

Matter Content ◽

Soil Organic Matter Content

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Effect of Clay, Soil Organic Matter, and Soil pH on Initial and Residual Weed Control with Flumioxazin

Agronomy ◽

10.3390/agronomy11071326 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1326

Author(s):

Calvin F. Glaspie ◽

Eric A. L. Jones ◽

Donald Penner ◽

John A. Pawlak ◽

Wesley J. Everman

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Weed Control ◽

Soil Ph ◽

Organic Matter Content ◽

Amaranthus Retroflexus ◽

Matter Content ◽

Weed Species ◽

Soil Organic Matter Content ◽

Field Soils

Greenhouse studies were conducted to evaluate the effects of soil organic matter content and soil pH on initial and residual weed control with flumioxazin by planting selected weed species in various lab-made and field soils. Initial control was determined by planting weed seeds into various lab-made and field soils treated with flumioxazin (71 g ha−1). Seeds of Echinochloa crus-galli (barnyard grass), Setaria faberi (giant foxtail), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf) were incorporated into the top 1.3 cm of each soil at a density of 100 seeds per pot, respectively. Emerged plants were counted and removed in both treated and non-treated pots two weeks after planting and each following week for six weeks. Flumioxazin control was evaluated by calculating percent emergence of weeds in treated soils compared to the emergence of weeds in non-treated soils. Clay content was not found to affect initial flumioxazin control of any tested weed species. Control of A. theophrasti, E. crus-galli, and S. faberi was reduced as soil organic matter content increased. The control of A. retroflexus was not affected by organic matter. Soil pH below 6 reduced flumioxazin control of A. theophrasti, and S. faberi but did not affect the control of A. retroflexus and E. crus-galli. Flumioxazin residual control was determined by planting selected weed species in various lab-made and field soils 0, 2, 4, 6, and 8 weeks after treatment. Eight weeks after treatment, flumioxazin gave 0% control of A. theophrasti and S. faberi in all soils tested. Control of A. retroflexus and Chenopodium album (common lambsquarters) was 100% for the duration of the experiment, except when soil organic matter content was greater than 3% or the soil pH 7. Eight weeks after treatment, 0% control was only observed for common A. retroflexus and C. album in organic soil (soil organic matter > 80%) or when soil pH was above 7. Control of A. theophrasti and S. faberi decreased as soil organic matter content and soil pH increased. Similar results were observed when comparing lab-made soils to field soils; however, differences in control were observed between lab-made organic matter soils and field organic matter soils. Results indicate that flumioxazin can provide control ranging from 75–100% for two to six weeks on common weed species.

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Assessment of Potato Farmland Soil Nutrient Based on MDS-SQI Model in the Loess Plateau

Sustainability ◽

10.3390/su13073957 ◽

2021 ◽

Vol 13 (7) ◽

pp. 3957

Author(s):

Yingying Xing ◽

Ning Wang ◽

Xiaoli Niu ◽

Wenting Jiang ◽

Xiukang Wang

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Fertility ◽

Soil Quality ◽

Soil Nutrients ◽

Organic Matter Content ◽

Soil Nutrient ◽

Matter Content ◽

Soil Organic Matter Content ◽

Farmland Soil

Soil nutrients are essential nutrients provided by soil for plant growth. Most researchers focus on the coupling effect of nutrients with potato yield and quality. There are few studies on the evaluation of soil nutrients in potato fields. The purpose of this study is to investigate the soil nutrients of potato farmland and the soil vertical nutrient distributions, and then to provide a theoretical and experimental basis for the fertilizer management practices for potatoes in Loess Plateau. Eight physical and chemical soil indexes were selected in the study area, and 810 farmland soil samples from the potato agriculture product areas were analyzed in Northern Shaanxi. The paper established the minimum data set (MDS) for the quality diagnosis of the cultivated layer for farmland by principal component analysis (PCA), respectively, and furthermore, analyzed the soil nutrient characteristics of the cultivated layer adopted soil quality index (SQI). The results showed that the MDS on soil quality diagnosis of the cultivated layer for farmland soil included such indicators as the soil organic matter content, soil available potassium content, and soil available phosphorus content. The comprehensive index value of the soil quality was between 0.064 and 0.302. The SPSS average clustering process used to classify SQI was divided into three grades: class I (36.2%) was defined as suitable soil fertility (SQI < 0.122), class II (55.6%) was defined as moderate soil fertility (0.122 < SQI < 0.18), and class III (8.2%) was defined as poor soil fertility (SQI > 0.186). The comprehensive quality of the potato farmland soils was generally low. The proportion of soil nutrients in the SQI composition ranged from large to small as the soil available potassium content = soil available phosphorus content > soil organic matter content, which became the limiting factor of the soil organic matter content in this area. This study revolves around the 0 to 60 cm soil layer; the soil fertility decreased gradually with the soil depth, and had significant differences between the respective soil layers. In order to improve the soil nutrient accumulation and potato yield in potato farmland in northern Shaanxi, it is suggested to increase the fertilization depth (20 to 40 cm) and further study the ratio of nitrogen, phosphorus, and potassium fertilizer.

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