Soil Available Phosphorus Investigated for Spatial Distribution and Effect Indicators Resulting from Ecological Construction on the Loess Plateau, China

Soil phosphorus is a major determinant and indicator of soil fertility and quality, and is also a source of nonpoint-source pollution. In order to control soil and water loss in the Loess Plateau, a series of soil and water conservation measures have been taken, resulting in changes in land use and differences in spatial distribution. It is necessary to study soil available phosphorus (SAP) to evaluate land productivity and environmental quality. In this study, the spatial distribution of SAP in different land uses was investigated in a small catchment area of Loess Plateau, and the field-influencing factors were determined on five layers with soil depth of 20 cm. The results show the minimum and maximum SAP content occurred at 20–40 cm and 80–100 cm soil depth and reach a value of 27.26 mg/kg and 29.37 mg/kg at catchment scale, respectively. There is significant difference among the SAP of the five soil layers (p < 0.01). The SAP of different land uses is, in order: forestland < slope farmland < dam farmland < terrace < grassland. Different land uses’ topographies make a difference to the spatial distribution of SAP. Slope and soil texture are the domain factors influencing the SAP concentration at the catchment.

Effect of Phosphorus Solubilizing Bacteria on Soil Available Phosphorus and Growth and Yield of Sugarcane

Phosphorus solubilizing bacteria (PSB) can increase soil phosphorus (P) availability and improve plant growth, yield, and phosphorus content of several crops. The experiment was conducted to evaluate the effect of PSB on soil available phosphorus, growth, and yield of sugarcane at field conditions. Kosakonia radicincitans (PSB1) and Bacillus subtilis (PSB2) were applied with two different sources of phosphorus fertilizers: Di-ammonium phosphate (DAP) and rock phosphate (RP). The application of PSB with phosphorus fertilizers enhanced the yield from 17.03 to 38.42 % over no application of fertilizer. It also increased the percentage of commercial cane sugar percent (CCS %) from 4.8 to 19.96 % over control. The application of PSB2 with DAP showed effective results in available phosphorus content in the soil and yield of sugarcane. The PSB population and the available phosphorus contents were higher in treatments when phosphorus was given partly through RP and DAP than the control. The application of phosphorus fertilizer and PSB increased phosphorus fractions in the soil. The addition of phosphorus fertilizer to soil increased all the inorganic phosphorus fractions in soil. The treatments with PSB resulted in statistical differences in total phosphorus concentrations in the soil. The application of PSB with RP (T6, T7, and T8) showed the highest weight among the treatment at the harvesting time. The yield of sugarcane was highest in the application of PSB2 with either DAP or RP (T4 and T7). HIGHLIGHTS Evaluate the effect of Phosphate Solubilizing Bacteria (PSB) (Kosakonia radicincitans and Bacillus subtills) comminated with two different phosphorus (di-ammonium phosphate (DAP) and rock phosphate (RP) fertilizers on the changes in the soil available phosphorus level and sugarcane growth at Sa Kaeo Province, Thailand The application of P fertilizer and PSB can increase the inorganic P fractions in the soil and increased the cane yield over NPK without PSB The PSB application either single or co-inoculation of PSBs increased the average cane more than 13 % to over control

Rapeseed Yield in a Maize – Rapeseed Cropping Pattern over a Long-Term Nutrient Management Experiment

A long-term soil fertility experiment in maize (Zea mays) – rapeseed (Brassica campestris var. toria) cropping system was initiated in Nepal Agricultural Research Council (NARC), Directorate of Agricultural Research (DoAR), Lumbini Province, Banke, Khajura (the then Regional Agricultural Research Station) since 1994. The field experiment was designed in the randomized complete block including nutrient as treatment at nine rates (0–0–0 nitrogen – phosphorus – potash (N–P2O5–K2O) kg/ha, 60–0–0 N–P2O5–K2O kg/ha, 60–40–0 N–P2O5–K2O kg/ha, 60–40–20 N–P2O5–K2O kg/ha, 30–20–10 N–P2O5–K2O kg/ha, 30–20–10 N–P2O5–K2O kg/ha + 30 cm stover from previous maize, 60–40–20 N–P2O5–K2O kg/ha + 30 cm stover from previous maize, farmyard manure 10 t/ha and 30–20–10 N–P2O5–K2O kg/ha + farmyard manure 6 t/ha) and was replicated three times. Rapeseed crop yield attributes including days to flowering, plant height, siliqua per plant, 1000 grains weight, seed yield and straw yield and soil fertility parameters including soil pH, soil organic matter content, soil total nitrogen content, soil available phosphorus content and soil available potash content were monitored from 1994 to 2018 growing seasons. There was a significant effect (p < 0.01) of nutrient treatments in the days to flowering, plant height, siliqua per plant, 1000 grains weight, seed yield and straw yield. The highest mean seed yield (445 kg/ha) was obtained from the nutrient application at the rate of 30–20–10 N–P2O5–K2O kg/ha + farmyard manure 6 t/ha during 1994 – 2018. Yield trend analysis revealed nutrient treatment with farmyard manure both FYM 10 t/ha and 30–20–10 N–P2O5–K2O kg/ha + FYM 6 t/ha had significant positive (p < 0.001, R2 > 0.30) trend of rapeseed seed yield with the maximum 1000 kg/ha rapeseed yield in 2018. Soil analysis results after rapeseed harvest in 2018 showed two nutrient treatments including farmyard manure had significant high soil organic matter (SOM > 1%), soil available phosphorus content (P2O5 > 55 kg/ha) and soil available potash content (K2O > 550 kg/ha). In the long-term, integrated nutrient management applying 30–20–10 N–P2O5–K2O kg/ha + FYM 6 t/ha was the optimal nutrient management option for rapeseed production in maize – rapeseed cropping system at Khajura and similar agro-ecological conditions.

Functional Diversity Can Predict Ecosystem Functions Better Than Dominant Species: The Case of Desert Plants in the Ebinur Lake Basin

Studying the impact of biodiversity on ecosystem multifunctionality is helpful for clarifying the ecological mechanisms (such as niche complementary effects and selection) of ecosystems providing multiple services. Biodiversity has a significant impact on ecosystem versatility, but the relative importance of functional diversity and dominant species to ecosystem functions needs further evaluation. We studied the desert plant community in Ebinur Lake Basin. Based on field survey data and experimental analysis, the relationship between the richness and functional diversity of dominant species and the single function of ecosystem was analyzed. The relative importance of niche complementary effect and selective effect in explaining the function of plant diversity in arid areas is discussed. There was no significant correlation between desert ecosystem functions (soil available phosphorus, organic matter, nitrate nitrogen, and ammonium nitrogen) and the richness of the dominant species Nitraria tangutorum (p < 0.05). Soil organic matter and available phosphorus had significant effects on specific leaf area and plant height (p < 0.05). Functional dispersion (FDis) had a significant effect on soil available phosphorus, while dominant species dominant species richness (SR) had no obvious effect on single ecosystem function. A structural equation model showed that dominant species had no direct effect on plant functional diversity and ecosystem function, but functional diversity had a strong direct effect on ecosystem function, and its direct coefficients of action were 0.226 and 0.422. The results can help to explain the response mechanism of multifunctionality to biodiversity in arid areas, which may provide referential significance for vegetation protection and restoration for other similar areas.

Urban-rural gradients in soil nutrients beneath Chinese pine (Pinus tabulaeformis Carr.) are affected by land-use

Urban-rural gradients of soil nutrients may be affected by many factors including land use, vegetation cover, and management. In this study, we investigated soil nutrients along urban-rural gradients beneath Chinese pine (Pinus tabulaeformis Carr.) in parks, neighborhoods and roadsides in Beijing, China. Soil levels of organic carbon, calcium, and magnesium are significantly higher in neighborhoods and parks than in roadsides. Soil nitrate-nitrogen levels are higher in neighborhoods than in roadsides. Soil magnesium levels are higher in neighborhoods than in parks. Interestingly, soil moisture, nitrate-nitrogen, calcium, magnesium, and available phosphorus and potassium all decreased in parks along the urban to rural gradient. Soil available phosphorus also declined along urban-rural gradients in neighborhoods. Thus, land use plays an important role in modifying urban-rural gradients of soil nutrients.

Vertical distribution of soil available phosphorus and soil available potassium in the critical zone on the Loess Plateau, China

Soil available phosphorus (SAP) and soil available potassium (SAK) are important elements in the growth of plants. However, limited data are available regarding the vertical distribution of SAP and SAK in deep soil profiles. In this study, we investigated the vertical variations in SAP and SAK in the critical zone on the Loess Plateau (50–200 m), China, by using classical statistical and geostatistical methods. The soil samples were collected from the top of the soil profile down to the bedrock by soil core drilling at five typical sites. SAP decreased throughout the profile. Whereas the SAK exhibited an increasing trend at all sites. The mean SAP concentration ranged from 0.94 to 32.56 mg kg–1 at the sampling sites and the SAK concentration ranged from 44.51 to 229.31 mg kg–1. At all of the sampling sites, SAK was significantly positively correlated with the depth and clay content, but there was a significantly negative correlation between the SAK and the sand content. The exponential model could fit most variograms of SAP and SAK at all sampling sites. The results obtained in this study to improve our comprehension of the SAP or SAK distribution conditions on the Loess Plateau, which is important for reasonable fertilizer application and vegetation planting practices.

Changes on available phosphorus and total nitrogen contents from soil around roots of two desert plants

In order to understand variation characteristics of the soil available phosphorus and total nitrogen (TN) content around the roots of typical desert plants Peganum harmala Linn. (PHL) and Asterothamnus centrali-asiaticus (AC), which are widely distributed in Jinchang mining area of Gansu Province, the soil samples around the roots of the two plants were collected, and the contents of available phosphorus and TN were analyzed. The results showed that the change trend of soil available phosphorus content was not the same in the range of 0-60 cm around the roots of PHL and AC. In most areas the change of available phosphorus content in the soil from around the root of PHL was U-shaped, and the content of phosphorus around the roots of AC increased firstly and then decreased, while the change trends of TN content around AC was decreased gradually.

Weed Management in Groundnut (Arachis hypogaea L.) with Phosphorus in Southern Rajasthan

Background: Agriculture sector is vital for food and nutritional security of the nation. Contrary to great stride in cereals and millets production during last few decades, desired rise in production of oilseeds has yet to be achieved though India has 14 and 9 per cent of global acreage and production.Methods: The present investigation was conducted during kharif seasons of 2016 and 2017, at Instructional farm, MPUAT, Udaipur to access the effect of different pre - post herbicides for weed control in groundnut under phosphorus application. This experiment was operated with six weed management practices and four phosphorus levels thus, 30 treatment combinations; all were evaluated in split-plot design with three replications.Result: Our investigations results revealed that herbicidal treatments as well as weed free check significantly control weed population and recorded the highest values of N, P, K concentration in weeds, kernel, biological yields and total chlorophyll content over weedy check while, significantly maximum N, P, K uptake and soil available phosphorus were noted under weedy check over rest of the treatments. Further, the results also showed that application of phosphorus exhibit significant increase in nutrient concentration and their uptake by weeds, kernel, biological yields, total chlorophyll content and soil available phosphorus over control during the course of investigation.

Effects of Field-Grown Transgenic Cry1Ah1 Poplar on the Rhizosphere Microbiome

Background: Poplar (Populus) is a genus of globally important plantation trees used widely in industrial and agricultural production. However, poplar is easily damaged by Micromelalopha troglodyta and Hyphantria cunea, resulting in a decline in poplar quality. Due to their strong insect resistance, Bt toxin-encoded Cry genes have been widely adopted in poplar breeding; however, potential adverse effects of Cry1Ah1-modified poplars on the ecological environment have raised concerns. Results: In this study, we comprehensively analyzed the structural and functional composition of the rhizosphere microbiome in field-grown transgenic Bt poplar. Conclusions: Our analysis of soil chemistry patterns revealed that soil alkaline nitrogen, soil available phosphorus, and microbial biomass nitrogen and phosphorus levels were improved, whereas microbial biomass carbon declined in Cry1Ah1-modified poplar rhizosphere samples. We applied metagenomic sequencing of Non-Transgenic (NT) and Cry1Ah1-modified poplar rhizosphere samples collected from a natural field; the predominant taxa included Proteobacteria, Acidobacteria, and Actinobacteria. We also identified microbial functional traits involved in membrane transport, amino acid metabolism, carbohydrate metabolism, and replication and repair in NT and Cry1Ah1-modified poplars. Together, these results demonstrate that the NT and Cry1Ah1-modified poplar rhizosphere microbiomes had similar diversity and structure. These differences in relative abundance were observed in a few genera but did not affect the primary genera or soil.

Influence of biochemical treatments on consortium of rhizobacteria and soil fertility

Soil was treated with different biochemicals i.e. NPK, compost, biochar, humic acid and their combination. New approach was designed to assess the impact of applied biochemicals on the activities of whole bacterial community in spite of pure isolates. The results showed that these biochemically mediated plant beneficial bacteria taken together efficiently solubilized the tri-calcium phosphate, when supplemented in Pikovskaya's broth (PKV). Phosphorus solubilization ranged from 0.231 to 0.605 μg/ml. The isolated consortium of rhizobacteria was positive for IAA production both with LB only and LB + tryptophan medium. The amount of IAA was increased by 0.25 - 1.5 folds with the addition of tryptophan to LB medium. These biochemical treatments were further tested for their effects on soil fertility improvement. Soil available phosphorus was found to improve significantly available phosphorus which ranged from 6.33 to 8.733 mg/kg. Soil pH, moisture content and organic matter were found to increase remarkably by the application of these treatments.