Equation to Predict Paddy Biomass Macronutrient Availability in Saline Soil Using Soil-Vegetation Indices from Multispectral UAV

Indonesia’s rice production has decreased by 6.83% (on average) in the last five years (2015 – 2019) because of some factors. Salinity (42%) is one of the leading factors that cause decreasing rice production besides climate change (21%), drought (9%), and other factors (28%). The smartphone camera serves as an alternative technology to prevent macronutrient deficiencies due to salinity. This study used aerial photos from android with visible light (R, G, and B), and the image was taken from a height of 5 m. The observation of macronutrient content in plant biomass was carried out using a free grid to adjust rice fields and saline soil. The formula was obtained from regression analysis and paired t-test between the biomass macronutrient and the extracted digital number of aerial photographs that have been stacked. The results showed that digital number (DN) from a smartphone was reliable to predict nitrogen (N), phosphorus (P), and potassium (K) content in rice with formula N = 0.0035 * DN + 0.8192 ( R 2 0.84), P = 0.0049 * DN – 0.2042 ( R 2 0.70), and K = 0.0478 * DN – 2.6717 ( R 2 0.70). There was no difference between the macronutrient estimation results from the formula and the field’s original data.

Os objetivos deste trabalho foram quantificar e avaliar as concentrações e conteúdos de macronutrientes na biomassa aérea de bracatinga (Mimosa scabrella Bentham) sob diferentes classes de sítio, idade e diâmetro. Ao todo, 25 árvores foram amostradas em diferentes bracatingais da região metropolitana de Curitiba, no Estado do Paraná. No campo, as árvores foram medidas e separadas nos seguintes compartimentos da biomassa: folhas, galhos < 4 cm, galhos ≥ 4 cm, madeira e casca do fuste. Posteriormente, amostras foram levadas ao laboratório para determinação da massa seca e macronutrientes. O efeito das classes de sítio, idade e diâmetro foram avaliados por meio de delineamentos estatísticos inteiramente casualizados. Os resultados encontrados indicaram que, as concentrações dos macronutrientes por compartimentos da biomassa apresentaram a seguinte ordem decrescente: folhas > casca > galhos > madeira. O compartimento da biomassa que apresentou os maiores conteúdos de macronutrientes foi a madeira. De acordo com os resultados, as concentrações de macronutrientes na biomassa aérea de bracatinga não apresentaram relação direta com as classes de idade e diâmetro e somente as concentrações de P e K nas folhas diminuíram da melhor para a pior classe de sítio. Não foram observadas relações de aumento ou diminuição entre os conteúdos de macronutrientes da biomassa de bracatinga e as diferentes classes de sítio e idade, entretanto, estes foram diretamente proporcionais aos diâmetros das árvores.

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The purpose of this study was to determine the remediation effect of various substances (manure, clay, charcoal, zeolite and calcium oxide) on limiting the influence of high cobalt doses (0, 20, 40, 80, 160 and 320 mg/kg of soil) on the content of macroelements in grain, straw and roots of oat. The doses of cobalt applied in this experiment as well as soil amendments such as manure, clay, charcoal, zeolite and calcium oxide had a significant effect on the content of the analysed macronutrients in grain, straw and roots of oat. In the series without any neutralising substances, the soil contamination with cobalt caused an increase in the content of nitrogen, phosphorus, sodium, calcium and, partly, potassium, in grain, straw and roots of oat. Among the neutralising substances tested, the most unambiguous effect was produced by manure, which raised the content of all macronutrients (except calcium and magnesium) in oat grain, straw and roots. The influence of the other substances on the content of macronutrients in oat plants was less equivocal. However, all of them, especially calcium oxide, tended to induce a decrease in the content of most macronutrients in grain, straw and roots of oat.

Knowledge regarding the behaviour and accumulation of nutrients in coffee berries and leaves is important information for the management of fertilisation. Therefore, this study aimed to evaluate the concentration and accumulation of macronutrients in coffee fruits and leaves under different fertilisation regimes in the south western Amazon, Brazil. The experiment was conducted in of plots subdivided by time: the main plots consisted of two fertilisation regimes (fertilised and unfertilised plants), and evaluation periods were in subplots (leaves: May 2013 to June 2014, fruits: July 2013 to April 2014). The experimental design was of randomised blocks with three replicates. Each experimental plot consisted of 11 plants; two productive plagiotropic branches were marked on each plant. Fruits were sampled every 28 days from the “pinhead” stage (July 2013) to maturation (April 2014). Twenty leaves were concomitantly sampled from each block until June 2014. The berries and leaves were dried in a convection oven and sent for laboratory chemical analysis. It was found that mineral fertilisation affects the concentration and accumulation of nitrogen, phosphorus, potassium, calcium and magnesium in berries and leaves. The concentration of macronutrients at the beginning of fruit formation is high and tends to decrease at later stages. In leaves, lower concentrations occur at the stage when the fruit is small and increase with growth. Most of the accumulation occurs in the expansion, bean formation and maturation stages the fruits.

The impact of salinity on paddy production in Indonesia was pronounced with an average decline of 6.83% (2015-2019). Salinity interferes with macronutrients' absorption into plants, causing stunted growth (salinity contributed to a 42% decrease in paddy production). One solution to solve the salinity problem in paddy is to use saline varieties. There were very few studies on macronutrient content analysis in resistant varieties response to the salinity source's distance. This research conducted in Jabon Sidoarjo, Indonesia, aims to see the macronutrient response and plant growth to the saline source's distance. This research was conducted in Jabon District, Sidoarjo Regency, using two transects with a length of 2 km and 3.4 km, respectively. The distance between the research location and the salinity source was 10.65 km. The survey used a free grid to adjust paddy fields' location and the presence of resistant varieties. The results showed that the closer to the salinity source, the salinity indicators consisting of Electrical Conductivity, Sodium Adsorption Ratio, Exchangeable Sodium Percentage, and pH H2O would increase. The increase in salinity then affects the decrease in macronutrients (Nitrogen, Phosphor, and Kalium) in plants. However, tillers and leaves (length and number) were unaffected by high salinity levels in the soil.

Impact of sewage sludge and composts prepared from sewage sludge on the content and uptake of macronutrients by straw of miscanthus sacchariflorus The pot experiment was set up under the conditions of the hall of vegetation in 2002. The municipal sewage sludge and composts produced with the GWDA method in 2001 based on municipal sewage sludge with the 30% addition of structuring materials, in conversion to the dry matter, were used in the experiment. The pot experiment was set up with the split-split-plot method in three repetitions. The objects of the first factor were the doses of sewage sludge and composts (1 dose = 13 g, 2 dose = 26 g, 3 dose = 39 g, 4 dose = 52 g of dry matter in relation to the soil weight in the pot), the objects of the second factor were the types of organic fertilization (sewage sludge, 0,5-year compost prepared from sewage sludge, 1,5-year compost prepared from sewage sludge), objects of the third factor were the variants with and without nitrogen and potassium fertilization in the rates of 0.27 g N and 0.26 g K per pot. The experiment was conducted in Kick-Brauckmann's pots of 9 dm3 capacity in which 8 kg of soil were placed. The test plant cultivated in the experiment was Miscanthus sachariflorus. Seedlings of Miscanthus were planted in the first year of the experiment. The obtained results show that the content of macronutrients: nitrogen, phosphorus, potassium in straw of Miscanthus sachariflorus was not dependent on the type of organic fertilizers used in the experiment. However, supplemental nitrogen-potassium fertilization significantly increases the content of potassium in the test plant in all three years of research and nitrogen in the second year. The conducted research shows that the uptake of macronutrients depended on the dry matter yield quantity and the content of a given element in the yield. Within three years the straw of Miscanthus sacchariflorus took up the most of potassium - 11.63 g from the pot and the least of magnesium 1.20 g from the pot. The amount of the absorption of nitrogen, phosphorus and magnesium by the biomass of Miscanthus sacchariflorus from the pot on the objects fertilized with organic fertilizers was the highest in the second year of the research, which was a result of mineralization of the applied fertilizers.

The hydrogeological and hydrogeochemical data of 75 groundwater samples and Landsat 8 OLI satellite data were used to identify the source and mechanism of groundwater and soil salinization in Femenin-Ghahavand aquifer (FGA) in Hamadan area, Iran. Generally, the EC values range from 350 to 7556μS/cm with a mean value of 1785μS/cm. The salinity value increases in the groundwater along the flow direction from southeast to northwest. The water samples are categorized into two water types of HCO3-Ca and Ca2+-Mg2+-Cl-. The water samples are super-saturated with calcite and dolomite due to dissolution of carbonate rocks through the flow path from recharge to discharge zones and under-saturated with respect to gypsum and halite. The most probable source of salinity is dissolution of interlayer of halite and gypsum in Miocene Marl and Qom formation in the bedrock of FGA. Also, the ion exchange is another major process that affects the deep groundwater quality in FGA. The water samples of FGA were divided into two groups based on the HFE diagram. About 71% of the samples are plotted below the mixing line, indicating intrusion process with reverse ion exchange and the rest (29%) is under freshening process with direct ion exchange. Consequently, the source of salinity in FGA groundwater is dissolution of halite and gypsum in deep saline groundwater which is likely upconing and mixing with fresh groundwater during overexploitation. The result of soil investigation using NDS index based on Landsat 8 OLI satellite data shows severe increase in salinization from 2013 to 2019. The areas with saline groundwater have saline soil too, indicating same source of groundwater and soil salinization. However, the main cause of soil salinization would be land use change and irrigation by saline groundwater and high evaporation in the region.

Studies have demonstrated that the physicochemical properties of saline soils can be improved, and crop growth can be promoted by fly ash saline and alkaline soil amendment materials. Herein, the effects of fly ash saline and alkaline soil amendment materials on the physical and chemical properties of saline soil and growth conditions of Arrhenatherum elatius at room temperature were evaluated. Meanwhile, planting experiments of Zea mays L. were conducted in the demonstration field of saline–alkaline land amendment in Yinchuan, Ningxia. The results showed that the application of amendment materials significantly (p < 0.05) improved saline soil’s physical and chemical properties. The saline soil pH decreased from an average of 10.51 to 8.89; the Na+ content decreased from an average of 2.93 g·kg−1 to 0.7 g·kg−1 after 25 days of action. In addition, the soil bulk density decreased from an average of 1.49 g·cm−3 to 1.36 g·cm−3, and the total porosity increased by 15.60%. Soil available phosphorus and available potassium content also increased significantly, with mean values increasing from 6.74 mg·kg−1 and 173 mg·kg−1 to 58.30 mg·kg−1 and 330.76 mg·kg−1, respectively. In addition, the plant height and stem thickness of Arrhenatherum elatius increased from an average of 11.76 cm, 1.28 mm to 21.72 cm, 1.59 mm with the application of 2.5 wt% amendment material. The plant height and stem thickness of Zea mays L. increased from mean values of 210 cm and 21.94 mm to 315.7 cm and 26.75 mm, respectively, when 0.07 t·hm−2 of amendment material was applied in the field. Overall, it was concluded that applying fly ash saline and alkaline soil amendment materials improves the physicochemical properties of saline soils, reducing saline stress and promoting the growth of Arrhenatherum elatius and Zea mays L.

Influence of composted manures and co-composted biochar on growth performance of saffron and soil nutrients under varying electrical conductivity soil conditions: A two-year field study

Fungi are an integral part of the nitrogen and phosphorus cycling in trophic networks, as they participate in biomass decomposition and facilitate plant nutrition through root symbioses. Nutrient content varies considerably between the main fungal habitats, such as soil, plant litter or decomposing dead wood, but there are also large differences within habitats. While some soils are heavily loaded with N, others are limited by N or P. One way in which nutrient availability can be reflected in fungi is their content in biomass. In this study, we determined the C, N, and P content (in dry mass) of fruiting bodies of 214 fungal species to inspect how phylogeny and membership in ecological guilds (soil saprotrophs, wood saprotrophs, and ectomycorrhizal fungi) affect the nutrient content of fungal biomass. The C content of fruiting bodies (415 ± 25 mg g-1) showed little variation (324-494 mg g-1), while the range of N (46 ± 20 mg g-1) and P (5.5 ± 3.0 mg g-1) contents was within one order of magnitude (8-103 mg g-1 and 1.0-18.9 mg g-1, respectively). Importantly, the N and P contents were significantly higher in the biomass of soil saprotrophic fungi compared to wood saprotrophic and ectomycorrhizal fungi. While the average C/N ratio in fungal biomass was 11.2, values exceeding 40 were recorded for some fungi living on dead wood, typically characterized by low N content. The N and P content of fungal mycelium also showed a significant phylogenetic signal, with differences in nutrient content being relatively low within species and genera of fungi. A strong correlation was found between N and P content in fungal biomass, while the correlation of N content and the N-containing fungal cell wall biopolymer-chitin showed only weak significance. The content of macronutrients in fungal biomass is influenced by the fungal life style and nutrient availability and is also limited by phylogeny.

Salinity-induced changes in the microbial use of sugarcane filter cake added to soil

Macronutrients (N, P, and K) are essential to plants but also can be harmful to the environment when their available concentrations in soil are excessive. Availability ratios (available concentration/total concentration) of macronutrients may reflect their transforming potential between fixed and available forms in soil. Understanding their spatial distributions and impact factors can be, therefore, helpful to applying specific measures to modify the availability of macronutrients for agricultural and environmental management purposes. In this study, 636 topsoil samples (0–15 cm) were collected from paddy fields in Shayang County, Central China, for measuring soil properties. Factors influencing macronutrient availability ratios were investigated, and total and available concentrations of macronutrients were mapped using geostatistical method. Spatial distribution maps of macronutrient availability ratios were further derived. Results show that (1) availability of macronutrients is controlled by multiple factors, and (2) macronutrient availability ratios are spatially varied and may not always have spatial patterns identical to those of their corresponding total and available concentrations. These results are more useful than traditional soil macronutrient average content data for guiding site-specific field management for agricultural production and environmental protection.

Saline soils are of great concern globally. Selecting the Yellow River Delta as a model site, the influence of reclamation on soil salinity and saline soil quality was investigated. Soil quality index (SQI) was applied to statistically analyze 210 soil profile samples collected at seven depth layers in 30 sampling sites among native saline soils and three croplands (peanut, cotton, and wheat) in May 2020. After reclamation, the soil salt content (SSC) reduced from 4.52 g/kg to 1.44 g/kg after reclamation, with the degree of soil salinity reducing from severe to slight. The nitrate nitrogen (NO3−-N) contents of peanut, cotton, and wheat croplands were 1.90, 2.02, and 4.29 times higher and the available phosphorus (AP) contents were 5.43, 3.57, and 8.77 mg/kg higher than that of the saline soils, respectively, while the soil ammonium nitrogen (NH4+-N) and available potassium (AK) contents were decreased. The NO3−-N, AN, and AP contents of the three croplands showed a significant surface aggregation at depth of 0–30 cm. SQI increased by 0.10, 0.09, and 0.02 after the reclamation with the enhancement effect of wheat and cotton was more pronounced. It was discovered that reclamation notably improved the soil quality as a result of crop growth and field management of fertilization and irrigation.

Around the world, especially in semi‐arid regions, millions of hectares of irrigated agricultural land are abandoned each year because of the adverse effects of irrigation, mainly secondary salinity and sodicity. Accurate information about the extent, magnitude, and spatial distribution of salinity and sodicity will help create sustainable development of agricultural resources. In Morocco, south of the Mediterranean region, the growth of the vegetation and potential yield are limited by the joint influence of high temperatures and water deficit. Consequently, the overuse of surface and groundwater, coupled with agricultural intensification, generates secondary soils salinity and sodicity. This research focuses on the potential and limits of the advance land imaging (EO‐1 ALI) sensor spectral bands for the discrimination of slight and moderate soil salinity and sodicity in the Tadla's irrigated agricultural perimeter, Morocco. To detect affected soils, empirical relationships (second‐order regression analysis) were calculated between the electrical conductivity (EC) and different spectral salinity indices. To achieve our goal, spectroradiometric measurements (350 to 2500 nm), field observation, and laboratory analysis (EC of a solution extracted from a water‐saturated soil), and soil reaction (pH) were used. The spectroradiometric data were acquired using the ASD (analytical spectral device) above 28 bare soil samples with various degrees of soil salinity and sodicity, as well as unaffected soils. All of the spectroradiometric data were resampled and convolved in the solar‐reflective spectral bands of EO‐1 ALI sensor. The results show that the SWIR region is a good indicator of and is more sensitive to different degrees of slight and moderate soil salinity and sodicity. In general, relatively high salinity soils show higher spectral signatures than do sodic soils and unaffected soils. Also, strongly sodic soils present higher spectral responses than moderately sodic soils. However, in spite of the improvement of EO‐1 ALI spectral bands by comparison to Landsat‐ETM+, this research shows the weakness of multispectral systems for the discrimination of slight and moderate soil salinity and sodicity. Although remote sensing offers good potential for mapping strongly saline soils (dry surface crust), slight and moderately saline and sodic soils are not easily identified, because the optical properties of the soil surfaces (color, brightness, roughness, etc.) could mask the salinity and sodicity effects. Consequently, their spatial distribution will probably be underestimated. According to the laboratory results, the proposed Soils Salinity and Sodicity Indices (SSSI) using EO‐1 ALI 9 and 10 spectral bands offers the most significant correlation (52.91%) with the ground reference (EC). They could help to predict different spatial distribution classes of slight and moderate saline and sodic soils using EO‐1 ALI imagery data.