Single Fertilizer Application Research Articles

Attapulgite application improves maize yield, water, and fertilizer utilization efficiency in newly cultivated sandy farmland in northwestern China

We determined the effects of attapulgite clay additions to sandy soils on maize yield and water-fertilizer use efficiency to evaluate a new method for enhancing productivity in newly-reclaimed farmlands in the oasis. The 2-year field trial included six treatments: no fertilizer, single fertilizer application (N–P2O5–K2O at 320–240–200 kg·ha−1), and combined applications of different amounts of attapulgite clay and fertilizer (attapulgite powder at 1500, 3000, 6000 kg·ha−1), 20% fertilizer reduction (256–192–160 kg·ha−1) and attapulgite powder at 6000 kg·ha−1. The results showed that maize yield increased by 4.9–14.9% and above-ground biomass increased by 6.1–32.3% with the application of 1500, 3000, and 6000 kg·ha−1 of attapulgite powder compared with the single application of fertilizer. With a combined application of a 20% reduction in fertilizer and 6000 kg·ha−1 attapulgite powder, maize yield increased by another 6.6%. Maize irrigation-water productivity (MIWP) increased by 0.03–0.13 kg·m−3, and nitrogen use efficiency (NUE), agronomic efficiency (AEN) and partial productivity factor of nitrogen (PFPN) increased by 10.8–54.0, 15.5–49.5, and 4.6–14.8%, respectively, compared with no attapulgite application. The contribution rate of fertilizer to maize yield increment improved by 10.0–30.1% with attapulgite application. The attapulgite clay application increased the field water capacity of sandy soils, nutrient retention in the 0–40 cm soil layer, and reduced nutrient leaching losses to deeper soils, thus improving water-fertilizer use efficiency. In Linze County, the abundant reserves of attapulgite clay may be used as a regular application in sandy farmlands in newly-reclaimed oases for a new promising way to rapidly improve sandy soil structure, enhance water-fertilizer use efficiency, and increase crop yields.

A single application of fertilizer can affect semi-natural grassland vegetation over half a century.

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland.

Branch Growth, Leaf Canopies and Photosynthetic Responses of Zizyphus jujube cv. “Huizao” to Nutrient Addition in the Arid Areas of Northwest China

Jujube is one of the main tree species found in the arid areas of Xinjiang, China. However, the nutritional requirements of central leader jujube trees are not understood. Our aim was to explore the effects of different fertilization gradients on the growth, development, and canopy formation of jujube trees to provide a basis for efficient cultivation. We measured and compared various suitable indices of jujube trees under 16 different fertilization treatments, and we confirmed the treatments suitable for cultivation by correlation and principal component analyses. The jujube tree growth indices under different fertilization treatments significantly differed (p < 0.05). The application of nitrogen fertilizer promoted the growth of branches and leaves. The soil and plant analyzer development value, light, and other traits significantly differed (p < 0.05). The leaf area index and direct transmittance coefficient significantly differed (p < 0.05). Compared with single-fertilizer application, mixed-fertilizer application significantly increased the leaf area index. Correlation analysis showed that the net photosynthetic rate of jujube leaves significantly correlated with the stomatal conductance, transpiration rate, and leaf SPAD content (p < 0.01). We obtained three principal components with a cumulative variance contribution rate of 82.192%. The final ranking showed that the mixed treatment (N 460.77 g/tree, P2O5 460.77 g/tree, and K2O 588.23 g/tree) performed better. To ensure branch and leaf growth, this treatment promoted photosynthesis, enabling the growth and development of fruit trees.

Soil Greenhouse Gas Emissions and Nitrogen Change for Wheat Field Application of Composted Sewage Sludge

This study aimed at assessing the character of greenhouse emissions under different rates of composted sewage sludge as a nitrogen fertilization substitute, founding the characteristic of soil nitrogen change and, ultimately, providing a theoretical basis for the rational utilization of composted sewage sludge in calcareous soil. Compost sludge as a nitrogen fertilizer substitute has emission reduction effects on N2O, CH4 and CO2. Compared with that of the single fertilizer application, the GHGI under the 20% sludge replacement treatment was significantly reduced by 20.15%, and the global warming potential was significantly reduced by 11.53%, while the wheat yield was increased by 4.78%. Compost sludge as a nitrogen substitute significantly increased the soil organic carbon at the jointing stage and reached a 100% replacement ratio at the maturity stage. During the jointing and mature stages, the total nitrogen content of the soil increased significantly at the 100% replacement ratio, while the soil nitrate nitrogen content only increased significantly at the 50% and 100% replacement ratio. Our findings highlight the impact of sludge compost on greenhouse gas emissions and soil nitrogen and guide the use of sludge compost in wheat fields.

Fertilizer Reduction Combined with Organic Liquid Fertilizer Improved Canopy Structure and Function and Increased Cotton Yield

The application of organic liquid fertilizer combined with chemical fertilizer is one of the key technologies used to simultaneously improve cotton yield and efficiently utilize resources. However, organic fertilizer is usually applied once as a base fertilizer during production, and few studies have been conducted on topdressing with water during the growth period. Therefore, in this study, Xinluzao 74 was used as the experimental material, and a single fertilizer application (CF) was used as a control in 2019–2020 under the conditions of integrated control of water and fertilizer with mulch drip irrigation. Five combinations of reduction in chemical fertilizer combined with organic fertilizer (OF1, OF2, OF3, OF4, and OF5) were used to investigate the influences of chemical fertilizer combined with organic liquid fertilizer on the leaf area index (LAI), canopy openness (DIFN), mean foliage tilt angle (MTA), photosynthetically active radiation (PAR), canopy apparent photosynthesis (CAP), and yield and quality of cotton. The results show that among the different fertilization treatments, the OF2 treatment had the best results, not only ensuring a suitable LAI (4.8) and maintaining a large DIFN (0.1) but also increasing the light transmittance of the middle and lower canopies (0.02–0.03). At the same time, CAP increased significantly compared with that in the CF treatment, with an average increase of 12.8%. The high value lasted for a long time, and the late decay stage remained at 8.9 μmol m−2 s−1. The ratio of the population respiration rate to total photosynthesis (CR/TCAP) decreased significantly, with an average decrease of 13.5%. Compared with that in CF, the lint yield increased by 27.0% in the other treatments. The correlation analysis showed that lint yield was positively correlated with the relative chlorophyll content (SPAD value), PAR transmittance (PARU) and CAP in the upper canopy (p < 0.05) and significantly negatively correlated with PAR transmittance (PARM) in the middle canopy and PAR transmittance (PARD) and CR/TCAP in the lower canopy (p < 0.05). Therefore, under mulch drip irrigation, the OF2 treatment (OF + 80% CF) improved the canopy structure of cotton at the late growth stage, increased the population photosynthetic rate, and increased lint yield significantly; thus, this approach can be used as an effective fertilization method to achieve the goal of decreasing costs and increasing efficiency in cotton production.

Controlled‐release nitrogen fertilizer management influences grain yield in winter wheat by regulating flag leaf senescence post‐anthesis and grain filling

AbstractControlled‐release nitrogen fertilizer (CRNF) is expected to meet the nutrient demands for crop growth with single fertilizer application, so as to achieve high‐yield, high‐efficiency, and labor‐saving cultivation. However, under current CRNF practices, a single application of CRNF in winter wheat (Triticum aestivum L.) usually fails to achieve satisfactory effects due to insufficient nitrogen (N) supply in the later growth stage, contributing to premature leaf senescence and poor grain filling. To determine a reasonable CRNF application strategy for improving the grain weight and yield of winter wheat, the responses of leaf senescence, photosynthetic capacity, grain‐filling characteristics, and grain yield to different CRNF types [polymer‐coated urea (PCU), sulfur‐coated urea (SCU), and urea‐formaldehyde (UF)] and fertilization practices [single fertilization (P1) and twice‐split fertilization (P2)] were investigated. The results showed that, compared with P1, P2 increased the activities of catalase, peroxidase, and superoxide dismutase, alleviated the accumulation of malondialdehyde, delayed flag leaf senescence, and enhanced the net photosynthetic rate (Pn) of the flag leaves, which promoted assimilate accumulation and transport to the grains. These advantages in P2 improved the grain‐filling process of wheat, with the active filling duration (T), average filling rate (G), and maximum filling rate (Gmax) in P2 all being higher than those in P1, which significantly increased the 1000‐grain weight (TGW) and grain yield of wheat. Among the three CRNFs, PCU showed advantages in Pn at the milk‐ripe stage (Zadoks growth stage, GS75), dry matter accumulation post‐anthesis, T, Gmax, and G, which contributed to TGW and grain yield. Overall, our study suggested that the twice‐split application of CRNF could substantially delay leaf senescence post‐anthesis and increase photosynthetic capacity, thus improving grain filling and productivity in winter wheat.

Single application of fertilizer in spring on timothy (Phleum pratense L.) dominant meadows using controlled release coated urea

Single application of fertilizer in spring on timothy (<i>Phleum pratense</i> L.) dominant meadows using controlled release coated urea

Hydroponic Fertilizer Supply for Basil Using Controlled-release Fertilizer

Small-scale hydroponics is a growing urban horticulture trend, but nutrient solution management remains a challenge for small growers. The objective was to investigate the potential to use controlled-release fertilizer (CRF) to simplify nutrient management in small-scale hydroponic systems. Three experiments were conducted with the goal of a single fertilizer application during the crop cycle of basil (Ocimum basilicum). Nutrient release curves were quantified by adding prills to water and measuring nutrient content weekly in the solution for CRF products without plants. In all seven products tested (Osmocote Bloom 2–3M, Osmocote Plus 3–4M, E-Max Calcium Nitrate 2–3M, Agrocote MAP 3–4M, E-Max Keiserite 3–4M, E-Max K-Mag 2–3M, and Agrocote SOP 3–4M) an initial rapid release was followed by a plateau, but release rates differed between products varying from 100% (MgSO4) to 60% release [(NH4).(H2PO4)] over an 11-week evaluation period. Total nutrient content in two commercial N–P–K CRF products (3–4 months 15N–3P–10K and 2–3 months 12N–3.1P–14.9K) provided lower Ca and Mg compared with a typical hydroponic solution based on water-soluble fertilizer (WSF). A subsequent experiment evaluated plant growth response using the same two commercial CRF products (single application) or a WSF (replaced weekly) in growth chamber environment. Plants grown for 4 weeks under CRF treatments yielded less than half the shoot fresh weight of plants grown with WSF and exhibited symptoms of Ca deficiency and micronutrient toxicity (confirmed with tissue analysis). Electrical conductivity (EC) of CRF solutions increased over time indicating excess dose compared with plant uptake, reaching a maximum of 5.4 dS·m−1. Nutrient release curves from the first experiment were then used to estimate product release and create a single-application nutritional program based on a customized “Blend” developed from CRF macronutrients plus WSF micronutrients. Plants were grown hydroponically with two dosages of Blend (1X and 2X) and compared with a commercial WSF with weekly replacement of solution. Blend 2X and WSF treatments had similar shoot fresh weight (241 and 244 g/four plants, respectively) with healthy plant appearance and tissue nutrient levels generally within published survey ranges for basil. Commercial CRF products designed for soil or container production were unsuitable for hydroponics, but acceptable plant performance with the customized CRF Blend demonstrated proof-of-concept for a single CRF application.

Influence of Microtopography and Soil Treatments on Tree Establishment on a Reclaimed Quarry

Research Highlights: Reclaimed minesites provide an opportunity to establish plantings of tree species of special concern, such as the American chestnut (Castanea dentata (Marshall) Borkh.), white oak (Quercus alba L.) and shortleaf pine (Pinus echinata Mill.). Background and Objectives: Reforestation success may be influenced by the physical and chemical characteristics of the substrate, which can be manipulated as part of the reclamation process. The objective of this study was to test the effects of three common reclamation treatments on the establishment of the above species on quarry overburden. Materials and Methods: This study tested the influence of lime and fertilizer (100 or 400 kg/ha N) application, loose dumped substrate vs. single pass grading and the resulting microtopography, on the survival and growth of planted 1:0 seedlings over seven years on reclaimed quarry overburden. Results: Grading had a negative impact on the survival of all species. Lime and fertilizer also influenced survival, but effects differed between species. A single application of fertilizer at the time of planting had a lasting and significant influence on the growth of all species. At year seven, across all species, microtopography influenced root collar diameter. The greatest growth was seen on the east upper, and west mid-slope positions. Conclusions: Fertilization and microtopography created by different site preparation techniques at the time of stand establishment can have a significant influence on tree growth over the first seven years.

Mepiquat chloride effects on potassium acquisition and functional leaf physiology as well as lint yield in highly dense late-sown cotton

Incredible accomplishments have been achieved in agricultural production in China, but many demanding challenges for ensuring sustainable cotton production remain. An efficient cropping model characterized with late sowing, higher density and low fertilizer application is a promising alternative to cope with the present high cost cotton production. However, it is not confirm that mepiquat chloride (MC) application is still required in this new planting model. We hypothesized that MC application might reduce lint yield and thus not be necessary in this new system. A 2-year (2015–2016) field experiment was performed to test this hypothesis in which cotton was planted in mid-May at 10 plants m−2 and with single fertilizer application (225 kg N ha-1). MC was sprayed thrice with 5 leaf intervals initiated from the 6th leaf stage in 5 different dosages i.e. 0 (control), 30, 60, 90, and 120 g ha-1. Morphological attributes viz. plant height, main stem diameter, number of fruiting branches, main stem nodes, main stem green leaves and main stem internode length were evidently reduced by 9–40%, 2–13%, 2–11%, 4–27%, 6–24% and 3–19%, respectively. Cotton potassium accumulation was not significantly influenced; specifically the uptake in reproductive organs from MC0 to MC120 of 45 to 44 kg K ha-1 in MC treated plants averaged across two years. Photosynthesis was reduced by 1–26% due to diminished Rubisco activity by 3–37% in MC treated plants and lint yield decreased by 5–27% as MC dosage increased. Furthermore, alpha amylase, beta amylase and total amylase activities were decreased by 2–16%, 3–19% and 1–17% but sucrose transformation rate was increased in the 4th functional leaf from the apex, respectively. Our data suggest that increased accumulation of sucrose and starch in the leaf with reduced photosynthesis, Rubisco and amylase activity could explain the yield loss. Conclusively, MC application is not needed for this new cotton planting model in Yangtze River Valley of China.

Potassium relative ratio to nitrogen considerably favors carbon metabolism in late-planted cotton at high planting density

A new planting model characterized with late sowing, high planting density, low N and single fertilizer application is much competitive to combat the present high cost cotton production. However, what is the optimal relative ratio of K to N under this model? as we understand it certainly plays a critical role in cotton production through a series of physiological processes. A two year (2016–2017) field experiment was conducted in a randomized complete block design with three K ratios relative to N [0.8 (K1), 1.0 (K2), and 1.2 (K3)] with four replications. Results showed that relative increase in K ratio had significant effect on functional leaf biomass, specific leaf weight, carbon metabolism as well as cotton yield in both growing seasons. K3 and K2 produced the similar seed cotton yield but higher than K1 in both years. Similarly, K3 and K2 prominently up-regulated the activity of ribulose 1, 5-bisphosphate carboxylase oxygenase (Rubisco), sucrose phosphate synthase (SPS) and sucrose synthase (SS) but down-regulated the activity of soluble acid invertase (SAI), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). Moreover, the balance of carbohydrates (sucrose, starch, glucose and fructose) and ATP was more efficient under higher K ratio (K3 and K2) as compared with K1. These findings might suggest that K rate should be equal to N as for promising yield and profitable return are concerned under newly proposed cotton planting model in the Yangtze River Valley of China.

Variability of Greenhouse Gas Footprints of Field Tomatoes Grown for Processing: Interyear and Intercountry Assessment.

Our study provides an integrated analysis of the variability of greenhouse gas (GHG) footprints of field-grown tomatoes for processing. The global farm-specific data set of 890 observations across 14 countries over a three-year period (2013–2015) was obtained from farms grown under Unilever’s sustainable agricultural code. It represents on average 3% of the annual global production of processing tomatoes: insights can be used to help inform corporate sourcing strategies and certification schemes. The median GHG footprint ranged from 18 in Chile to 61 kg CO2-equiv per tonne of tomatoes in India, lower than results reported in other studies. We found that footprints are more consistent within countries than between them. Using linear mixed effect models, we quantified the relative influence of environmental conditions and farm management factors. Key variables were area of production and the method of fertilizer application. GHG footprints decreased with increasing area of production to a threshold of 17.4 ha. Farms using single fertilizer application methods in general had a larger GHG footprint than those using a combination of methods. We conclude that farm management factors should be prioritized for future data collection, and more stringent guidance on acceptable practices is required if greater comparability of outcomes is needed either within a scheme, such as the Unilever’s sustainable agriculture code, or between schemes.

Initial Effects of Fertilization and Canopy Management on Flowering and Seed and Oil Yields of Jatropha curcas L. in Malawi

Appropriate canopy management, including planting density and pruning, and application of fertilizer may increase flowering success and seed and oil yields of Jatropha curcas L. Two field experiments were performed from 2009 to 2011 in Balaka, Malawi, to assess the effect of planting density and pruning regime and single fertilizer application (N, P, and K) on male and female flower number and seed and oil yields of J. curcas. Planting density influenced flower sex ratio and female flower number. Branch pruning treatments did not influence the flower sex ratio but reduced seed and final oil yield by 55 % in the following year. It is claimed that J. curcas can be grown on soils with low nutrient content, but this study revealed that yield was low for non-fertilized trees. We observed higher seed and oil yields at higher N application rates (up to 203 ± 42 % seed and 204 ± 45 % oil yield increase) compared with the non-fertilized control. The study suggests thatcurrently used heavy pruning practice is not recommended for J. curcas cultivation, although it needs further longer term investigation. Applying nitrogen fertilizer is effective in increasing yield.

Rainfall amount and distribution regulate DMPP effects on nitrous oxide emissions under semiarid Mediterranean conditions

Nitrogen fertilizer application timing and the use of nitrification inhibitors are currently promoted as agronomic practices with potential to reduce nitrous oxide (N2O) emissions. However, the efficacy of these practices is to a large extent regulated by weather variability, particularly rainfall and temperature. This is primarily the case for rainfed crops under semiarid Mediterranean climate, where large fluctuations occur in the amount and frequency of rainfall from year to year. In this 3-year field experiment, we explored the potential of fertilizer application timing and a nitrification inhibitor (3,4-dimethyl pyrazole phosphate; DMPP) to achieve low N2O, for a rainfed barely (Hordeum vulgare L. cv Pedrezuela) crop under a semiarid Mediterranean climate. Five fertilizer management practices were tested: split fertilizer application at planting and at tillering with (1) or without DMPP (2); the same split fertilizations but applying DMPP only at tillering (3); and single fertilizer application al tillering with (4) or without DMPP (5). During the dry conditions of year 1, the application of DMPP reduced N2O emissions (up to 72%) whereas timing of fertilizer application had no effect. Conversely, under the wet conditions of year 2 the effect of DMPP was suppressed but fertilizer timing was successful diminishing N2O, with lower emissions measured with single fertilizer application at tillering. In year 3, where rainfall distribution was remarkably erratic, N2O emissions were mitigated by both DMPP and single fertilizer applications. Overall, our results show that DMPP offers an opportunity for N2O abatement in semiarid soils under Mediterranean environments. The low moisture content of these soils during long periods favors nitrification; by inhibiting this process, products such as DMPP are able to achieve large N2O reductions. Although single fertilizer application at tillering as opposed to the traditional split application at planting and tillering may provide a management opportunity for N2O mitigation, we also found that this practice may lead to yield reductions in years with sufficient rainfall in spring. Therefore, general implementation of this practice should not be encouraged.

Quantifying and reducing the water footprint of rain-fed potato production part II: a hydrological assessment using modelling supported by measurements

Abstract Water footprinting (WF) is mooted to quantify the impacts of production on water resources. The impact of the rain-fed potato ( Solanum tuberosum) production on water resources was assessed for a kilogram of potatoes at the packhouse gate. The hydrological water-balance method was used and this accounts for all inflows and outflows to quantify the net use of groundwater as the blue WF, and that of the soil-water store as the green WF. The green WF was found to be negligible. The blue WF was negative at −67 L/kg. Thus rain-fed potato production here has no deleterious impacts on the water quantity. The grey WF, the water required to ‘dilute’ NO 3 –N in the drainage to meet the drinking water standard, was 61 L/kg, of which 56 L/kg was from the cropping stage. The impact of the packhouse phase and the background system was found to be small. However, the average leached NO 3 –N concentration of 11.3 mg/L, which is just at the drinking water standard, and the loading of 27.8 kg-N/ha/y during cultivation indicate that a single application of fertilizer at the time of planting has impacts on water quality. Our modelling of different fertilizer application scenarios of two splits, three splits and a late application at 55 days after planting reduced the annual average NO 3 –N concentrations to 10.5, 10.3 and 9.5 mg/L respectively. Potato yield was not compromised. The grey WF would be reduced to 50.6, 50.9 and 48.9 L/kg respectively for these fertilizer scenarios.

Research on Method of Single Fertilizer Application to be Suitable for Barley in Niigata

Research on Method of Single Fertilizer Application to be Suitable for Barley in Niigata

Adaptive optimization of crop production and nitrogen leaching abatement under yield uncertainty

The study develops a bio-economic crop management model that internalizes the environmental cost of nitrate pollution, accounts for stochastic weather, and includes an option for split fertilization. The integrated model is designed to indicate whether a producer can benefit from applying fertilizer several times during the growing season, in response to crop needs, rather than a single time, at sowing. The model is parameterized for the cultivation of spring malting barley ( Hordeum vulgare L.) in Southern Finland. The costs of negative externalities from nitrogen leaching are internalized in the landowner’s decision problem through a pollution tax. The results indicate that without a pollution tax a single application of fertilizer gauged to meet the needs of the entire season is optimal. With a tax, the benefits of split application – applying varying amounts of fertilizer at selected stages of the growing season – increase significantly. In comparison to a single application of fertilizer at sowing, split fertilization improves yields, increases the total amount of fertilizer used, and reduces nitrogen leaching.

Modeling Nitrate Leaching and Optimizing Water and Nitrogen Management under Irrigated Maize in Desert Oases in Northwestern China

Understanding water and N transport through the soil profile is important for efficient irrigation and nutrient management to minimize nitrate leaching to the groundwater, and to promote agricultural sustainable development in desert oases. In this study, a process-based water and nitrogen management model (WNMM) was used to simulate soil water movement, nitrate transport, and crop growth (maize [Zea mays L.]) under desert oasis conditions in northwestern China. The model was calibrated and validated with a field experiment. The model simulation results showed that about 35% of total water input and 58% of the total N input were leached to <1.8 m depth under traditional management practice. Excessive irrigation and N fertilizer application, high nitrate concentration in the irrigation water, together with the sandy soil texture, resulted in large nitrate leaching. Nitrate leaching was significantly reduced under the improved management practice suggested by farm extension personnel; however, the water and nitrate inputs still far exceeded the crop requirements. More than 1700 scenarios combining various types of irrigation and fertilizer practices were simulated. Quantitative analysis was conducted to obtain the best management practices (BMPs) with simultaneous consideration of crop yield, water use efficiency, fertilizer N use efficiency, and nitrate leaching. The results indicated that the BMPs under the specific desert oasis conditions are to irrigate the maize with 600 mm of water in eight times with a single fertilizer application at a rate of 75 kg N ha(-1).

Recreating a Functioning Forest Soil in Reclaimed Oil Sands in Northern Alberta: An Approach for Measuring Success in Ecological Restoration

During oil-sands mining all vegetation, soil, overburden, and oil sand is removed, leaving pits several kilometers wide and up to 100 m deep. These pits are reclaimed through a variety of treatments using subsoil or a mixed peat-mineral soil cap. Using nonmetric multidimensional scaling and cluster analysis of measurements of ecosystem function, reclamation treatments of several age classes were compared with a range of natural forest ecotypes to discover which treatments had created ecosystems similar to natural forest ecotypes and at what age this occurred. Ecosystem function was estimated from bioavailable nutrients, plant community composition, litter decomposition rate, and development of a surface organic layer. On the reclamation treatments, availability of nitrate, calcium, magnesium, and sulfur were generally higher than in the natural forest ecotypes, while ammonium, P, K, and Mn were generally lower. Reclamation treatments tended to have more bare ground, grasses, and forbs but less moss, lichen, shrubs, trees, or woody debris than natural forests. Rates of litter decomposition were lower on all reclamation treatments. Development of an organic layer appeared to be facilitated by the presence of shrubs. With repeated applications of fertilizers, measured variables for the peat-mineral amendments fell within the range of natural variability at about 20 yr. An intermediate subsoil layer reduced the need for fertilizer and conditions resembling natural forests were reached about 15 yr after a single fertilizer application. Treatments over tailings sand receiving only one application of fertilizer appeared to be on a different trajectory to a novel ecosystem.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi