Leaching Losses Of Nutrients Research Articles

Potential of artificial soil preparation for vegetation restoration using red mud and phosphogypsum

Red mud and phosphogypsum have long been a focus and challenge in global industrial waste management, and their low-cost and large-scale utilization technology has always been an urgent need. This study is based on the strong acid-base neutralization reaction between red mud and phosphogypsum, which contain an elemental composition similar to that of natural soil, red mud itself has characteristic of clay minerals, and other auxiliary materials (i.e. rice husk powder, bentonite, fly ash, polyacrylamide flocculant and microbial suspension) were added, so as to explore the potential of synergistically prepared artificial soil for vegetation restoration. The results showed that the artificial soils exhibited physicochemical characteristics (e.g., pH, moisture content, cation exchange capacity) similar to those of natural soil, along with abundant organic matter, nitrogen, phosphorus, and potassium contents, meeting the growth requirements of plants. The artificial soils were able to support favorable growth of suitable plants (e.g., sunflower, wheat, rye grass), accumulating high levels of diverse enzymatic activities, comparable to those in natural soils (e.g., catalase, urease, phosphatase), or even surpassing natural soils (e.g., sucrase), and rich microorganism communities, such as Cyanobacteria, Proteobacteria, Actinobacteria in the bacteria domain, and Ascomycota in the fungi domain, were initially developed. It's suggested that preparing 1 ton of artificial soil entails synergistic consumption of 613.7 kg of red mud and 244.6 kg of phosphogypsum, accounting for mass proportions of 61.4 % and 24.5 %, respectively. In future, more evaluations on the leaching loss of nutrients and alkalinity and the environmental risks of heavy metals should be conducted to more references for the artificial soil application. In summary, the preparation of artificial soil is a very simple, efficient, scalable and low-cost collaborative resource utilization scheme of red mud and phosphogypsum, which has great potential for vegetation restoration in some places such as tailings field and soil-deficient depression.

The effects of bio-based superabsorbent polymers on the water/nutrient retention characteristics and agricultural productivity of a saline soil from the Yellow River Basin, China

To investigate the effects of superabsorbent polymers (SAPs) on the water/nutrient retention characteristics and agricultural productivity of a saline soil from the Yellow River Basin, soil column leaching and pot experiments were carried out. Three types of SAPs were used: a commercial SAP (CSAP), a starch-grafted SAP (SGSP), and a modified SGSP (MSSP). Six treatments were set up in the leaching experiment, including MS (MSSP alone was applied), CF (chemical fertilizer alone was applied), CF+CS (chemical fertilizer and CSAP were applied), CF+SS (chemical fertilizer and SGSP were applied), CF+MS (chemical fertilizer and MSSP were applied), and CF+ 70%MS (chemical fertilizer and MSSP were applied, but MSSP dosage was 70% of that in CF+MS). Six treatments were set up in the pot experiment as well, including CK (no fertilizer or SAP was applied), MS, CF, CF+CS, CF+SS, and CF+MS. Results of the leaching experiment showed that water and nutrient leaching loss from the saline soil was reduced by 12.6–22.7% and 14.2–65.0%, respectively, in the treatments with SAP application. In addition, both soil pore number and soil porosity were significantly increased in the 0–10 cm soil layer. In the pot experiment, maize yield was increased by 25.9–32.1% and fertilizer use efficiency was significantly increased with the application of SAP. Taken together, SAP application in the saline soil improved soil moisture and nutritional conditions and promoted crop growth. This work provides a reference for improving crop productivity and water management of the large area of saline soils in the Yellow River Basin.

Biochar-Swine Manure Impact on Soil Nutrients and Carbon Under Controlled Leaching Experiment Using a Midwestern Mollisols

Biochar application to the soil can improve soil quality and nutrient leaching loss from swine manure adapted soils. Our working hypothesis was that the biochar-incubated with manure could be a better soil amendment than conventional manure application. The manure-biochar application to the soil would decrease nutrient leaching from manure and increase plant-available nutrients. The study objectives were to 1) assess the physicochemical properties of the manure-biochar mixture after lab incubation and 2) evaluate the impact of biochar-treated swine manure on soil total C, N, and other major and minor nutrients in comparison to conventional manure application to soil. Three biochars 1) neutral pH red-oak (RO), 2) highly alkaline autothermal corn (Zea mays) stover (HAP), and 3) mild acidic Fe-treated autothermal corn stover (HAPE) were incubated with swine manure for a month. The biochar-manure mixture was applied in triplicate to soil columns with an application rate determined by the P2O5-P content in manure or manure-biochar mixtures after the incubation. The ammonium (NH4+), nitrate (NO3‒), and reactive P concentrations in soil column leachates were recorded for eight leaching events. Soil properties and plant-available nutrients were compared between treatments and control manure and soil. Manure-(HAP&HAPE) biochar treatments significantly increased soil organic matter (OM), and all biochar-manure mixture increased (numerically) soil total C, N, and improved soil bulk density. Concentrations of NH4+and NO3‒significantly increased in MHAPE column leachates during this 4-week study and the KCl-extractable NH4+and NO3‒in the soil at the end of the experiment. A significant reduction in soil Mehlich3 Cu was also observed for the manure-HAPE mixture compared with the manure control. The manure-red oak biochar significantly increased the soil Mn availability than other manure-biochar treatments or manure control. Overall, the manure-biochar incubation enabled biochar to stabilize the C and several nutrients from manure. The subsequent manure-biochar mixture application to soil improved soil quality and plant nutrient availability compared to conventional manure application. This proof-of-the-concept study suggests that biochars could be used to solve both environmental and agronomic challenges and further improve the sustainability of animal and crop production agriculture.

Assessing Nutrient Leaching Loss Using Nonweighing Lysimeters in Acidic Soils of Eastern Plateau and Hill Region of India

ABSTRACT Leaching losses of nutrients in the winter crops of tomato and pea cultivated in acidic soils of the eastern plateau and hill region were studied using nonweighing type lysimeters under different nutrient management practices involving the control (T1), inorganic (T2), organic (T3), and integrated (organic + inorganic, T4) sources of nutrients. The leaching loss of nutrients varied significantly among various fertilizer management practices and the rate of loss differed among the nutrients. The treatment receiving 100%-recommended dose of NPK as inorganic form (T2) recorded highest N, and K leaching loss of 22.1, 14.8 kg ha−1 in tomato accounting 13.7% and 21.1% of the applied fertilizer, while in pea, it was 9.14 and 10.8 kg ha−1, respectively, accounting 20.3% and 20.4% of the applied fertilizer. The P-leaching loss was comparatively less and the differences among the treatments were statistically nonsignificant. The fruit yield of tomato was significantly highest (44.8 t ha−1) in the treatment with integrated fertilizer sources (T4), which was 52.7% higher over control (T1). The pod yield of pea was highest (11.3 t ha−1) in T3 and was 59.7% higher over control.

Arbuscular mycorrhizal fungus-induced decrease in nitrogen concentration in pore water and nitrogen leaching loss from red soil under simulated heavy rainfall.

Arbuscular mycorrhizal fungus (AMF) is generally colonized in plant roots and influences the migration of mineral elements such as nitrogen (N) in soils. However, its effect on N leaching loss in red soils is limited. In the present study, red soils were collected from wasteland, farmland, and slopeland in the Yunnan Plateau. Maize, as a host plant, was cultured in a dual-compartment cultivation system. There were mycorrhizal and hyphal compartments for the AMF inoculation treatment and root and soil compartments for the non-inoculation treatment. The N concentration and uptake in maize, N concentration in pore water within two depth (0-20 and 20-40 cm), and N leaching losses from soil under simulated heavy rainfall (40 and 80 mm/h) were analyzed. Results showed that AMF inoculation significantly enhanced the biomass and N uptake in maize. Compared with the root and soil compartments, the N concentrations in pore water and their leaching losses from the mycorrhizal and hyphal compartments were decreased by 48-77% and 51-74%, respectively. Moreover, significant or extremely significantly positive correlations were observed between the N concentrations in pore water with the N leaching losses from soil. The three-way ANOVA showed that AMF highly significantly decreased N concentrations in pore water and their leaching losses from wasteland, farmland, and slopeland; rainfall intensity had strong influences on the N concentration in pore water from farmland and N leaching losses from wasteland and farmland, whereas the maize root's effect was insignificant. The study indicated that the AMF-induced decreases in the N leaching loss from red soils were caused by increased N uptake by maize and decreased N concentrations in pore water. These results have implications for reducing nutrient leaching loss through the management of beneficial microorganisms in soils.

Trends of Lysimeter Studies to Investigate Nutrient Leaching Loss

Lysimeter is used to monitor water and nutrient transport through soil profiles under minimum disturbance conditions. In this study, we focused on the researches about nutrient leaching loss using a lysimeter in the world. We aimed at reviewing key studies and planning further research directions using the weighable lysimeters in Korea. In response to climate changes, environmental issues, and policies for sustainable agriculture, the experiments using a lysimeter were performed to better understand the nutrient leaching loss in the soils. The research topics were about crop rotation, soil amendment, nitrification inhibitors and what were better practices for reducing nutrient leaching including nitrogen. In addition, some researches focused on developing optimal models to predict the nutrient leaching loss in the soils that have a variety of environments. Current study suggests that the studies of the nutrient leaching loss combined with water dynamics using weighable lysimeters in Korea are to be fostered so that they may provide scientific guidelines on the issues and policies such as sustainable agriculture, climate change, fertilizer recommendation, and nutrient balance. Lysimeter research topics on nutrient leaching in Korea and around the world.

Preparation and properties of novel corn straw cellulose–based superabsorbent with water‐retaining and slow‐release functions

ABSTRACTIn this study, novel semiinterpenetrating polymer networks (semi‐IPNs) superabsorbent resins with slow‐release fertilizer (CSC‐g‐AA/APP, CSC‐g‐AA/PVA‐APP), based on corn straw cellulose polymer and linear polyvinyl alcohol (PVA), were prepared by solution polymerization. The nitric acid‐aqueous solution method was adopted to extract cellulose from corn straw. Ammonium polyphosphate (APP) was introduced to supply nitrogen and phosphorus nutrients. The prepared materials were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Moreover, the water absorbency and the slow‐release performance of CSC‐g‐AA/APP and CSC‐g‐AA/PVA‐APP were studied. The results indicated that the two superabsorbent resins exhibited excellent water absorbency of 262.8 and 303.2 g/g in distilled water, enhanced the water‐holding capacity of soil, and also released nutrients slowly. The cumulative N and P release rates of CSC‐g‐AA/PVA‐APP were 64.47 and 53.53% after 25 days in soil, which were lower than those of CSC‐g‐AA/APP. The addition of these products into soil significantly reduced the leaching losses of nutrients. Therefore, it can be concluded that the superabsorbent resins with water‐retaining and slow‐release properties, low production costs, and environment‐friendly characteristics, have great potential for applications in agricultural production. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48951.

Banana peel biochar as alternative source of potassium for plant productivity and sustainable agriculture

PurposeBiochar addition to soil is immensely beneficial for increasing plant productivity and C sequestration, attenuating nutrient leaching loss, counteracting heavy metal contamination and organic waste triggered environmental pollution. To understand the sustainable benefits of biochar, two pot experiments were conducted under net house condition in Khulna University, Bangladesh.MethodsBiochar was prepared from banana peel waste through slow pyrolysis process under limited oxygen condition. Three lower rates (1, 2 and 3%) of banana peel biochar (BPB) were added with agricultural soil along with control with three replications for each. After incorporation of BPB into soil, pots were kept under field condition for 7 days and then the seeds of Ipomoea aquatica were sown. Plants were harvested after 42 days from seeds sowing and plant height, leaf number, fresh weight, and dry weight were measured. Another pot experiment was also conducted under sand medium to test the BPB as K-rich soil amendment where K was applied from two different sources (KCl and BPB) along with control. Seeds of Cucurbita moschata were sown and 40 days after seed sowing, K deficiency was observed in control treatments.ResultsBanana peel biochar was found to be rich in K content. Plant productivity and above-ground biomass were reduced in 1% BPB treatments, but increased in 2 and 3% BPB treatments as compared to control but statistically insignificant (p < 0.05). In case of second experiment, K deficiency symptoms were observed in 40 days aged Cucurbita moschata seedlings under control treatments, whereas no K deficiency symptom was noticed in plants grown under K supplied from both KCl and BPB. Moreover, the plant grown with BPB was found healthy, stronger and greener in appearance.ConclusionThis positive influence of BPB on plant growth suggests the alternative way to overcome the use of chemical fertilizer and effective way of utilization of agricultural wastes through recycling.

Nutrient Leaching Loss of Pre-Treated Struvite and Its Application in Sudan Grass Cultivation as an Eco-Friendly and Sustainable Fertilizer Source

Struvite recovered from waste streams is considered as a sustainable alternative to commercial phosphate (P) fertilizers manufactured from P rock. In this study, struvite was recovered from swine wastewater and pre-treated as air-dried material (AM), microwave irradiated material (MM), oven-dried material (OM), and incinerated material (IM) to reduce the moisture content. Based on their solubility and crystalline nature, AM and IM were selected for further experiments. The nutrient leaching loss and fertilizing value of AM and IM were evaluated in comparison to commercial fused superphosphate (FSP) fertilizer. Soil columns were used to quantify ortho-phosphate (O-P) and ammonium nitrogen (NH4-N) leaching in soil from the test materials. Among the test materials, the average leaching rate of O-P for FSP and AM was significantly different from the control and IM (p &lt; 0.05). The average leaching rate of NH4-N among the test materials did not show any significant difference (p &gt; 0.05). Sudan grass growth was examined with standard (urea supplemented) and high (20x, without urea) application of test materials in pot and soil box trials, respectively, to study the fertilizing value AM and IM. There were no significant differences among the test materials, except for the control, in terms of growth rate and fresh and dry matter yield in the pot trials (p &gt; 0.05). When AM, IM, and FSP were applied in increasing amounts (20x) without urea supplement, Sudan grass growth was 50% lower in IM and was found to be significantly different from AM and FSP (p &lt; 0.05). The results suggest that struvite pre-treated as AM could be an effective sustainable and eco-friendly alternative to commercial P fertilizers and thus helps to ensure agricultural sustainability.

Rice plant growth and nutrient leaching under different patterns of split chemical fertilization on sandy soil using a pot

Savannakhet Province has 25% of the total lowland rice cultivation area of Lao People’s Democratic Republic (Laos). However, most of the fields are rainfed, with highly permeable sandy soil, which has low water and nutrient availability. In such sandy rainfed fields, high leaching loss of nutrients from applied fertilizer is expected, and rice yield is also decreased. Therefore, an efficient fertilization scheme is required to improve rice yield in this area. We conducted a pot experiment to evaluate rice plant growth and nutrient leaching under different split chemical fertilizer application patterns. Sandy soil collected in a village in Savannakhet Province was placed in test pots. Four treatments, viz., standard fertilization (control: C, three splits), subdivided fertilization (SF, six splits), intensive fertilization (IF, once at the time of transplanting), and no fertilizer (NF) were tested. Irrigation was done every 3 days during the initial 3 months and every 10 days in the final month with reference to the rainfall pattern recorded in the rainy season of 2016. Although the maximum number of tillers in C and IF was higher than that of SF, they ultimately decreased to a smaller number than that of SF. The yield of SF was higher than that of the other three treatments. NF showed the lowest growth and yield. The six-split fertilization might supplement nitrogen (N) at the late growing stage. IF showed the largest N leaching loss among treatments. Because of low phosphorus (P) leaching loss, split P fertilization was ineffective. K leaching was completed by 39 days after transplanting, suggesting that all of the K applied by fertilizer and irrigation was consumed by rice plants or lost through leaching before panicle initiation. The proposed split fertilization is advantageous in that it supplies N for panicle initiation and maturing stages in sandy paddy fields, but the timing and amount of P application must be considered.

Title “Organic Fertilizers” in Vietnam’s Markets: Nutrient Composition and Efficacy of Their Application

Organic fertilizers have recently been gaining popularity; however, their governance is not completely assessed in developing countries. This study investigated the nutrient composition of so-called organic fertilizers in Vietnam’s markets and issues related to their production, and evaluated their potential to contaminate the groundwater. We analyzed the physicochemical properties of 12 domestic and four imported products of the fertilizers, and conducted a cultivation experiment in sandy soil with the fertilizer applied at a rate of 200 mg N kg−1 soil using an automatic watering apparatus in a greenhouse. We further studied the production of an “organic fertilizer” from coffee by-products. The nutrient content greatly varied among domestic products, whereas they were quite similar among imported products. The product packaging of the collected samples lacked information regarding raw materials. Two thirds of the domestic products contained over 30% of the total N in the inorganic form, implying that the N content dramatically increased in the fertilizers rather than in their supposed raw materials. The stages involved in the production were composting, the addition of extra soil as a bulking agent, and the mixing-in of chemical substances to increase the nutrient content before packing. The remarkably high ratio of inorganic N to total N was attributed to excessive N leaching from soil by the application of domestic fertilizers. These results suggested the need for quality criteria guidelines for organic fertilizers in Vietnam that underline not only nutrient levels, but also the control of raw materials and production process of compost, because they are closely related to nutrient uptake and the leaching loss of nutrients.

Effect of Fertilizer Management on NPKS Leaching Loss from Sandy Loam Soil under Alternate Wetting and Drying Condition

Leaching loss of nutrients hampers plant growth and contributes to environmental pollution. An experiment was conducted at the net house of Soil Science Department, Bangladesh Agricultural University, Mymensingh during January to May 2009 to find out the leaching loss of N, P, K and S from sandy loam soil. Each pot received 6.67 kg dry soil with an opening at the bottom for collecting leachates. Six treatments were used: T0 = control, T1 = NPKS (120, 25, 60 and 20 kg ha-1), T2 = NPKS (180, 37, 90 and 30 kg ha-1), T3 = NPKS (90, 5, 28 and 17 kg ha-1) + cowdung (2.5 t ha-1), T4 = NPKS (109, 25, 60 and 20 kg ha-1, N as USG) and T5 = as T1 but N applied as foliar spray. Treatments were arranged in a completely randomized design with three replications. Leachates were collected at 15 days interval for determination of NPKS. The total leaching loss of N, P, K and S due to different treatments ranged from 16.00 to 90.21, 0.07 to 0.29, 9.60 to 11.20 and 3.75 to 17.81 kg ha-1, respectively. Application of chemical fertilizer at higher rates resulted in greater loss of nutrients. Integrated fertilizer management with cowdung (T3) minimized such losses. Use of USG also reduced leaching loss of N, P, K and S. The application of cowdung and USG with recommended balanced fertilizer might be useful for minimizing N, P, K and S loss from wetland rice field.Bangladesh Rice j. 2016, 20(1): 59-64

Composting and gypsum amendment of broiler litter to reduce nutrient leaching loss.

The effect of composted litter relative to fresh litter on leaching losses of nutrients has not been well documented. Fresh and composted broiler litter was surface-applied to bermudagrass (hay) [ (L.) Pers.] established in undisturbed soil columns based on N need of the grass in the presence or absence of flue gas desulfurization (FGD) gypsum to evaluate an approach to reduce broiler litter nutrient leaching potential. Columns were periodically leached and biomass was harvested during the 60-d experiment. Total N applied to bermudagrass from broiler litter was 320 kg ha. Gypsum was mixed with fresh and composted litter at the rate based on 20% of litter weight. For composted broiler litter, NO-N, P, K, Cu, and Zn contents in the leachate obtained from the first leaching event were 58, 50, 40, 32, and 38% less than fresh broiler litter, respectively. Significant decreases in NO-N (13%), P (53%), Cu (17%), and Zn (28%) in leachate were obtained when gypsum was mixed with fresh broiler litter. Fresh broiler litter and composted broiler litter applications increased bermudagrass growth compared with the control and gypsum significantly increased yields when mixed with broiler litter. Composted broiler litter application significantly increased N and organic C in the soil compared with fresh litter. Results demonstrate that coapplication of composted broiler litter with FGD gypsum provide the most effective management option for minimizing leaching losses of nutrients while sustaining crop productivity.

Nutrient leaching in an Ultisol cultivated with sugarcane

Solute leaching below the crop-rooting zone represents not only a valuable loss of nutrients for the plant, but also a potential pollution source of groundwater. The objective of this work was to quantify nutrient-leaching losses at 0.9m depth in an Ultisol that was cultivated with sugarcane, located in the county of Jaboticabal-SP, Brazil. The following ions were evaluated: nitrite, nitrate, ammonium, sulfate, phosphate, calcium, magnesium and potassium. The first ratoon cycle was monitored from November 16, 2006, to July 9, 2007. The experimental design was organized as four random blocks and three treatments: T1: without fertilizer; T2: 100kgha−1 of N and 114kgha−1 of S; and T3: 150kgha−1 of N and 172kgha−1 of S. To determine the fate of the N-fertilizer and S-fertilizer, four microplots were installed, in which 2.15% atoms of 15N- and 10.5% atoms of 34S-enriched ammonium sulfate were applied. The input and output of anions and cations were quantified from the flux density of water and the ion concentration. The NO3−, K+, Mg2+ and Ca2+ concentrations in the soil increased in January following both rainfall and drainage. The leaching of N was between 3.9 and 34.9kgha−1. The N leached derived from the 100kgha−1 applied N fertilizer was 22.5kgha−1. The S leached was between 4.6 and 8.4kgha−1. From the 114kgha−1 S applied as fertilizer the leaching was 0.480kgha−1. The maximum leaching of P, K, Ca, and Mg were 1.2, 53.6, 135.7 and 39.8kgha−1, respectively. From the results, it is not possible to determine whether the local groundwater will be contaminated, but caution should be taken to maintain soil quality by reducing the leaching loss of nutrients.

Production of slow release crystal fertilizer from wastewaters through struvite crystallization – A review

Nitrogen and phosphorus in wastewaters are a burning environmental issue of the present world. This review covers the studies conducted on the removal and recovery of phosphorus and nitrogen from wastewaters through struvite crystallization. Wastewater which contains a high amount of phosphorus and nitrogen would be a good source of struvite. Struvite is a phosphate fertilizer, although it contains a significant amount of nitrogen and magnesium, and it is an effective alternative source of rock phosphate to maintain the agricultural production system. The present review deals with the principles and concept of struvite nucleation, crystal growth and the factors that affect on the struvite quality. Struvite precipitation occurs in an equimolecular concentration of Mg2+, NH4+ and PO43− at slightly alkaline conditions. Addition of a source of Mg is essential to maintain the favorable condition of PO4 and Mg. Different factors such as Mg:PO4 molar ratio, pH, aeration rate, reactor types, as well as P and N removal efficiencies were also discussed throughout this review. The slower nutrient leaching loss and its fertilizer quality make struvite an eco-friendly fertilizer. It is possible to overcome the acute shortage of rock phosphate if all the municipal and livestock wastewaters are connected with the wastewater treatment plants.

Recovery of struvite from animal wastewater and its nutrient leaching loss in soil

Contaminants in swine wastewater were recovered in the form of struvite, a crystal of magnesium ammonium phosphate (MAP), using a newly designed process, and the leaching loss of MAP in soil was examined. The continuous flow process was operated under optimal conditions: 1.0 molar ratio of magnesium (Mg) addition with respect to orthophosphate (OP) and an aeration rate of 0.73L/Lmin. Five treatments were performed with three replications for soil pH and nutrient leaching loss tests. It was found that 93% of the OP in the swine wastewater was crystallized, and the MAP crystal formation was verified by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The analyses revealed that the pattern of pH change and N leaching losses for MAP-treated soil were remarkably different from those for fused super phosphate (FSP)-urea-treated soils. The pH levels for the control and FSP-urea-treated soils after a five-week experiment were unchanged or slightly decreased, whereas an increase in pH was observed in the MAP-treated soils. Leaching loss of N was higher in FSP-urea treatments, with MAP treatments showing N losses of only 1.93 and 2.05%, respectively, while FSP-urea treatments showed N losses of 7.82 and 6.47%, respectively, during the same period. Phosphate (P) leaching was very slow in both MAP- and FSP-treated groups.

Nutrient Dynamics Through Leachate and Turf Grass Growth in Sands Amended with Food‐Waste Compost in Pots

Nutrient dynamics through leachate by intermittent irrigation and turf grass growth was monitored in sands amended with food‐waste compost (FWC) and chemical fertilizer (CF) in pots. The present study was carried out to evaluate the subsequent effects of FWC amendment in sands on probable nutrient dynamics/losses and turfgrass growth in pot cultivation. The plants were grown 170 days in pots and nutrient dynamics/losses were evaluated in four different stages. The maximal nitrogen (N) loss occurred as nitrate (NO3)‐N, which was higher in FWC than CF treatment. Initially, the loss of N as ammonium (NH4)‐N was prominent. Fast N loss was observed in CF, which was totally exhausted by 134 days after sowing of turf grass seeds. Because of slow‐release characteristics, the nutrient losses were delayed in FWC, and it took comparatively longer periods (about 170 days) for near‐exhaustion of N. The FWC amendment enhanced K retention and decreased its leaching loss compared to P in the present observation. Elevated concentrations of salts leached out, and the electrical conductivity (EC) in the leachate was proportionately maintained with the amount of FWC application. The amount of salt dissociation and EC of leachate were inversely correlated with N uptake and shoot dry‐matter production. The total N uptake by shoot was higher in FWC‐amended treatments until later stages of turf grass growth but was much lower in CF‐treated plants. Comparatively, the FWC pellets treatment showed superior performance over sole FWC in sustaining nutrients in growing media. Finally, longer retention of nutrients with better performance in plant growth was observed in FWC‐amended treatments in spite of higher leaching loss of nutrients.

Man-made Versus Natural Forests in Mid-Yunnan, Southwestern China

Plant diversity, water, and soil conservation of man-made versus natural forests in Mouding (25°24′09″ N, 101°28′18″ E), mid-Yunnan, were investigated and analyzed. Various plant communities exist in this mountainous region: 4-year-old shrubland, a 10- to 14-year-old plantation of Eucalyptus smithii, a 35- to 45-year-old plantation of Pinus yunnanensis, a 35- to 45-year-old semi-natural forest of Keteleeria evelyniana and Pinus yunnanensis, a 35- to 55-year-old natural secondary forest of Keteleeria evelyniana and Cyclobalanopsis glaucoides, and a climax forest of Cyclobalanopsis glaucoides, Castanopsis orthacantha and Castanopsis delavayi as the original mid-subtropical, semi-moist, evergreen broad-leaved trees in the region. The species diversity and the regenerative quality were poorest under the Eucalyptus forest. The Pinus forest had the lowest interception and stemflow (26.4%) of rainfall, followed by the Eucalyptus forest (29.5%). The leaching loss of nutrients was greater in the two planted forests than in the natural ones. The soil under the Eucalyptus forest was impoverished and showed deterioration of its chemical characteristics, as compared to the shrubland, semi-natural, natural, secondary, and climax forests in the same area.

Foliar leaching of 137Cs from Eriophorum vaginatum L., Scirpus caespitosus L. and Erica tetralix L.

Evidence of extensive leaching losses of nutrients, particularly of K, suggest that loss of 137Cs by foliar leaching could be considerable and could stimulate further root uptake and redistribution of 137Cs in plants. This study investigated the foliar leaching of 137Cs from two deciduous graminoid species, Eriophorum vaginatum and Scirpus caespitosus and one evergreen shrub, Erica tetralix. Plants were labelled with 137Cs via the roots and subjected to a leaching treatment in August and November and changes in both leachate and plant 137Cs activity were determined. Leaching losses were significantly reduced in November compared with August in the deciduous species, but not in the evergreen E. tetralix. A reduction in the total activity of 137Cs of leached plants was observed not only in leaves but also in stems and roots in some instances, suggesting that 137Cs from these organs had been redistributed to replenish that lost by leaching from the leaves. The data suggest that leaching losses were greater from older and senescent leaves than from younger leaves of E. vaginatum. The extent to which this is an accurate representation of foliar leaching of field-grown plants by rainfall, and the likely fate of 137Cs lost by foliar leaching are discussed.

Temporal patterns of soil nutrients in a Panamanian moist forest revealed by ion-exchange resin and experimental irrigation

The effect of seasonal water availability on soil nutrients and soil N transformations was investigated by irrigating two large plots of mature tropical forest on Barro Colorado Island (BCI), Panama, during the dry season for five consecutive years. Methods included (i) nutrient accumulation by ion-exchange resins placed on the surface of the mineral soil for contiguous 21-day periods, (ii) monthly mineral soil (0–10 cm) extractions and incubations for inorganic N and P concentrations, and (iii) leaching loss of nutrients from leaf litter samples. Rates of nutrient accumulation by the resins showed a great deal of variation between sampling dates and among years in control plots; albeit, seasonal patterns were slight, except for the highest Ca values near the end of the wet season and inorganic P (Pi) and SO4 values that peaked during the dry season. Irrigation had remarkably little effect on nutrient accumulation rates by resins, except for an increase in Mg and Na values, but did affect the timing in the temporal variation in K, Na, Ni and Pi values. In contrast, inorganic N (Ni) and Pi pools and N transformation rates in the mineral soil hardly varied among sampling dates and did not show any response to irrigation. We hypothesize that the timing of leaf litterfall and nutrient leaching from forest floor litter can set up temporal patterns in the levels of soil nutrient at the surface of the mineral soil, but the temporal patterns essentially disappear with depth in the mineral soil.