Unfertilized Control Treatment Research Articles

Response to side-banded phosphorus and zinc fertilizer for corn grown after canola or soybean in southern Manitoba

A 2-year crop rotation study in southern Manitoba assessed the effects of starter fertilizer on grain corn ( Zea mays L.) production when corn followed canola ( Brassica napus L.) versus soybean ( Glycine max L. Merr.). Treatments included a control (no starter) and two rates of phosphorus (P) (30 and 60 kg P2O5 ha−1) as monoammonium phosphate (MAP, 11–52–0) or MicroEssentials® SZ (MESZn, 12–40–0–10–1) side-banded at planting. The preceding crop did not have any influence on mycorrhizal colonization of corn roots at the V4 corn growth stage. However, side-banded fertilizer increased early-season biomass by as much as 111% compared to the unfertilized control, averaged across all site-years, with the largest increases occurring where corn followed canola. P concentration and uptake in early-season biomass increased as the P rate increased. Zinc (Zn) concentrations in early-season biomass were the greatest for the unfertilized control and MESZn treatments, while Zn uptake was significantly greater with the application of starter fertilizer compared to the unfertilized control. Starter P advanced silking date by 2–7 days relative to the unfertilized control. At maturity, starter P reduced grain moisture by 21–27 g kg−1 in corn only after canola. The high rate of MAP increased grain yield by an average of 770 kg ha−1 compared to the unfertilized control, regardless of the preceding crop. The negative influence of the preceding canola crop on early-season growth and mid-season development of corn can be managed with starter fertilization to provide adequate P and Zn to the corn crop and maintain successful production in Manitoba.

Using bio-based fertilizer derived from peri‑urban wastes affects soil properties and lettuce yield and quality

The use of waste-derived fertilizers, also known as bio-based fertilizers (BBFs), for the production of ready-to-eat vegetables can efficiently contribute to sustainability and circularity. However, studies on the efficiency and safety of these fertilizers are needed. Thus, this study aimed to examine and characterize the effects of combined application of BBFs on lettuce yield and quality and soil properties in a trial conducted under open field conditions. The eight experimental treatments included green- or food waste compost combined with either human urine, food waste digestate or synthetic fertilizer and compared to treatments with synthetic fertilizer alone or in combination with manure. The control treatment received no BBF or other type of fertilizer. The results showed statistically similar fresh lettuce yields after 48 days among the treatments, all of which were larger than the yield of the unfertilized control treatment. The highest fresh yield (73 t ha−1) was observed with the combination of manure and synthetic fertilizer. Yield in treatments that received green waste or food waste composts tended to decrease slightly, more likely due to nitrogen immobilization after the application of incompletely stabilized composts and the low initial mineral N. Nitrate contents in fresh lettuce leaves were below the EU limits (3000 mg kg−1) in all the treatments. Analysis of pathogens and trace elements present in aboveground lettuce showed no significant risk. The application of BBFs also appeared to maintain the soil pH compared to synthetic fertilizer treatments. The important nutrient and carbon contents of BBFs and their positive effect on lettuce yield associated with their non-harmful impact on lettuce quality suggest that BBFs can be used for vegetable production and to increase the soil carbon stocks and contribute to city sustainability.

Enhancing Fertilizer Effect of Bioprocessed Brewers’ Spent Grain by Microbial Consortium Addition

Brewers’ spent grain (BSG) is primarily recycled as livestock feed due to its high fiber content, undegradable protein, and water-soluble vitamins. However, BSG composting represents a possible alternative to organic waste management. Adding a microbial consortium further enhances the agronomical properties of the compost intended for fertilizing applications. Microbial-based fertilizers (plant growth-promoting microorganisms, PGPM) are a means to mitigate the adverse environmental impacts of excessive or improper chemical fertilizer use, enhance the direct or indirect uptake of nutrients by plants, and add value to food waste. In a short-term pot experiment on iceberg lettuce (Lactuca sativa L.), this study assessed the effects of compost and pelletized compost from brewers’ spent grain, both enriched with a microbial consortium. In a randomized block experiment, this study compared four organic BSG fertilizers to chemical fertilizer (NPK) and an unfertilized control treatment. The investigation indicates that BSG compost and BSG pelleted compost, with and without bio-inoculum, in general, are comparable to mineral fertilizer treatment; lettuce fresh weight was higher in pots amended with bioprocessed BSG, associated with more significant growth of soil LAB, fungi, and actinomycetes. The investigation outcomes support composting as an alternative recycling process for producing PGM for agricultural applications.

Long-term bioorganic and organic fertilization improved soil quality and multifunctionality under continuous cropping in watermelon

Continuous cropping has can majorly damage the soil ecosystem, leading to an increased prevalence of pathogenic microorganisms and severe yield losses for watermelons. Multiple prevention strategies have been adopted to overcome this obstacle, among which the application of bioorganic fertilizer can improve microbiome deterioration. However, the response of soil ecosystem multifunctionality and soil quality to fertilizer regimes under continuous cropping remains poorly understood. In this study, based on an 8-year field experiment, we evaluated soil health and ecosystem multifunctionality under different fertilization treatments. Long-term bio-organic fertilization preserved soil electrical conductivity and increased total Cu, Zn, Fe, Mn, Ca, and Mg, total and available nutrients, and enzyme activities compared with those in unfertilized control (CK) and chemical fertilizer treatments. Enzyme activities and yield rapidly changed, indicating their sensitivity to these management practices. Conversely, soil pH, biodiversity, medium/trace elements, and total NPK content were more resistant to change than enzyme activities, suggesting higher stability over time. The area of soil quality index under bio-organic fertilization was 1.2–2.9 times larger than that under CK treatment. Applying biological organic fertilizer and a mixture of chemical and organic fertilizers improved the multifunctionality decline caused by continuous cropping by 1.1–1.4 times, whereas the effect of the chemical fertilizer was weak. Soil health was positively correlated with ecosystem multifunctionality. These findings suggest that long-term bioorganic and organic fertilization is an effective strategy for improving soil quality and multifunctionality in continuous watermelon crops while also contributing toward a more sustainable agricultural system.

Tillage and nitrogen rate effects on winter wheat yield in a wheat–sorghum rotation

The objectives of this study were to quantify long-term tillage practice and nitrogen (N) fertilizer rate effects on yield and N use in a winter wheat ( Triticum aestivum L.)–grain sorghum ( Sorghum bicolor L. Moench)–fallow (W–S–F) rotation. The experimental design was a randomized complete block with a split–split-plot arrangement. The main plot treatments were crop rotation phases W–S–F, S–F–W, and F–W–S. The sub-plots were tillage practices, i.e., conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). And the sub-sub-plot treatments were N rates of 0, 45, 90, and 134 kg ha−1. Wheat yield increased at rates of 15.6, 9.3, 22.8, and 25.7 kg ha−1 for a kg N ha−1 increase in very low-, low-, high-, and very high-yielding environments (average yields of ∼2000, 2500, 2800, and 4400 kg ha−1), respectively. On average, winter wheat yields were 7%–9% greater for CT compared with both NT and RT. Winter wheat removed about 52 kg N ha−1 from the unfertilized control treatment, but N uptake varied by N rate and growing conditions. Nitrogen use efficiency, N agronomic efficiency, and applied N recovery decreased as the N rate increased. Across environments, wheat yield increased by 16, 20, and 17 kg ha−1 for each additional kg ha−1 N applied under CT, NT, and RT, respectively, and additional 2–2.5 kg ha−1 yield increases for a mm increase in fallow precipitation. We concluded that wheat yield response to N is highly dependent on growing conditions, and NT required greater N fertilization than CT and RT for similar yields.

Fertilization Strategies on Fennel Crop in the Mediterranean Environment: Agronomic Performance, Costs and Sustainability Assessment

In the Mediterranean area, using organic fertilizers is crucial to maintaining and increasing soil fertility and crop productivity since soil organic matter is being progressively depleted due to climate change effects. Therefore, the aim of this study was to compare two different organic fertilizers (MC1 without and MC2 with an inoculum of selected microorganisms), applied at 100% and 50% doses, with mineral fertilization and an unfertilized control: (i) by assessing the agronomic performance of fennel crop; and (ii) by investigating environmental and economic sustainability, through GHG emissions determination, carbon efficiency, and cost analysis. The results of the MC2 were comparable to the mineral fertilization for crop growing parameters (plants and roots dry weights) and marketable yield, irrespective of the amount applied (50–100%), likely due to the inoculum of selected microorganisms. These may have favored the soil microbial activity, the nutrient availability, and better synchronization of N mineralization with fennel N demand with respect to MC1 (with a higher C/N ratio). The MC2 also achieved lower costs than the other treatments. The highest GHG emission value was found in the mineral fertilization treatment, while the lowest was recorded in the unfertilized control treatment. The two organic treatments at 100% were the most carbon-efficient systems because of the highest carbon stocks/output, considering the difference between C stocked/output and the C loss/input emitted.

Aggregate mass and carbon stocks in a paddy soil after long‐term application of chemical or organic fertilizers

AbstractThe soil organic carbon stock that accumulates in soil aggregates as a result of the practice of fertilizer application is important for sustainable agriculture and for mitigating the effects of climate change. In this study, we investigated how the practice of fertilizer application affects the mass of soil aggregates and carbon stocks in surface and subsoil layers in rice paddy soil. We determined the mass and carbon concentration in different size classes of aggregates in soil in the top 40‐cm layer after the long‐term application of different fertilizers. We found that the amount of organic carbon in bulk soil and aggregates decreased with increasing soil depth, except free microaggregates (free‐m, 250–53 µm), which showed the opposite trend. Macroaggregates (>250 µm) were the main type of soil particles in both surface soil and subsoil. Compared with the unfertilized control or chemical fertilizer treatments, manure or straw combined with chemical fertilizers significantly (p < 0.05) increased the mass and carbon concentration in small macroaggregates (2000–250 µm) and small macroaggregate fractions in the surface soil (0–20 cm), whilst the opposite effect was detected for large macroaggregates (>2000 µm) and large macroaggregate fractions. In the top 40‐cm soil layer, the carbon content in small macroaggregates and most small macroaggregate fractions increased linearly with increasing carbon input rate, but that in large macroaggregates and most large macroaggregate fractions decreased. Overall, small macroaggregates were the dominant particle size class harbouring carbon stocks, and the subsoil in this paddy soil has a high potential for carbon sequestration.

Liquid Organic Fertilizer Effects on Growth and Biomass of Lettuce Grown in a Soilless Production System

Demand for locally produced, organically grown leafy greens is increasing throughout the United States. However, due to lack of efficient organic fertilizers (OFs) for soilless substrates, organic greenhouse production of leafy greens may be challenging. Therefore, a greenhouse study was conducted to analyze the effects of six liquid OFs on growth and development of lettuce in a soilless system. Two experiments were conducted using a randomized block design, and treatments included six fish- or plant-based OFs: OF1 (5N–1P–1K), OF2 (2N–5P–1K), OF3 (3N–1P–1K), OF4 (2N–2P–2K), OF5 (4N–1P–1K), and OF6 (3N–3P–2K); one inorganic fertilizer treatment (IF, 24N–8P–16K); and one unfertilized control treatment. Fertilizer solutions were prepared at 2 dS⋅m–1 and applied at 100 mL/plant. In Expt. 1, fresh biomass for IF-treated plants was 12% to 38% greater than OF treatments, whereas this difference ranged from 25% to 57% in Expt. 2. Similarly, leaf area values of IF-treated plants were 5% to 40% greater than OF treatments in Expt. 1, and the difference ranged from 28% to 90% in Expt. 2. A possible explanation could be greater availability of nutrients in the IF treatment compared with OF treatments. There was no significant difference among fertilized treatments for number of leaves and stem diameter. Based on the index-based ranking, fish-based (OF1) and fish- and plant-based (OF2 and OF6) performed well among different liquid OFs used in the study. Although the yield under OFs was less compared with that under IF, there is potential to reduce this yield gap by optimized fertility management of these fertilizers. Future research is needed to investigate the impact of optimized rate, timing, different placement, and additional nitrogen (N) sources of OFs on the soilless production of lettuce.

Optimizing interaction between crop residues and inorganic N under zero tillage systems in sub-humid region of Kenya

Conservation agriculture practices involving zero tillage and residue retention are promising nutrient management strategies for soil health restoration. Despite their potential positive impact on soil fertility, improved crop yields and increased revenues for smallholder farmers; their effect on nitrogen inputs and crop growth is not clearly understood. This may limit their potential as a nutrient management strategy that may remedy soil degradation and boost crop yields for farmers. This study investigated how different tillage practices, crop residues and inorganic nitrogen (N) options affect maize production, soil fertility and economics of smallholder farming systems. The study was conducted in a short-term (2 years) on-station trial, under randomized complete block design with three replications in a maize monocrop system. Six treatments, involving three different rates of maize stover residue (0, 3 and 5 t ha−1) and inorganic N (0, 3 and 5 t ha−1) inputs, respectively, were assessed under conventional and zero tillage systems. Mineral N and organic C were assessed at four depths (0–10 cm, 10–30 cm, 30–60 cm and 60–90 cm) whereas soil aggregate distribution was assessed at 0–5 cm, 5–10 cm, 10–15 cm and 15–20 cm depths. Application of inorganic N as the only input increased (p ≤ 0.05) grain yield (with the yields doubling in the short rains (SR) of 2015 and increasing by 1.4 times in long rains (LR) of 2016) compared to unfertilized control treatment. Treatment, soil depth and the time of sampling significantly affected soil mineral N concentration (p ≤ 0.05). Soil organic C reduced significantly (p ≤ 0.05) with sampling depths, but no differences were observed across treatments. At 0–5 cm depth, the proportion of large macroaggregates in zero tillage increased (48%; p ≤ 0.05) after application of crop residues at 5 t ha−1 relative to 3 t ha−1. Zero tillage treatment with application of 5 t ha−1 of residue and 80 kg N ha−1 was the most dominant and most profitable compared to the other treatments. This treatment had a benefit cost ratio (BCR) of 2.9 (in the short rains season of 2015) and 3.0 (long rains of 2016 seasons). Its marginal rate of return (MRR) was 368% (in the 2015 short rains season) and 416% (in the 2016 long rains season). This makes it a good nutrient management strategy with potential of optimizing maize yields.

Ecosystem Services and Cash Crop Tradeoffs of Summer Cover Crops in Northern Region Organic Vegetable Rotations

Intensive production practices characterizing vegetable farming contribute to high productivity, but often at the expense of supporting and regulating ecosystem services. Diversification with cover crops may support increased resilience through soil organic matter (SOM) contributions and physical soil protection. Vegetable farming often includes spring and fall production, limiting establishment and productive potential of over-wintered cover crops that are more widely used in the USA. In northern climate vegetable systems, warm-season cover crops planted during short summer fallows could be a tool to build resilience via ecosystem service enhancement. This project evaluated summer cover crops in the northern USA (MN and WI) for biomass accumulation, weed suppression, and contribution to fall cash crop yield. Our study included four site years, during which we investigated the effects of four cover crop species treatments, grown for 30 (short duration, SD) or 50 days (long duration, LD) alongside bare fertilized and unfertilized control treatments: buckwheat (Fagopyrum esculentum) and sunn hemp (Crotalaria juncea) monocultures, and biculture of chickling vetch (Lathyrus sativus) or cowpea (Vigna unguiculata) with sorghum-sudangrass (sudex) (Sorghum bicolor x S. bicolor var. Sudanese). To quantify cover crop quantity, quality, and weed suppression capacity, we measured cover crop and weed biomass, and biomass C:N. To quantify effects on cash crops, we measured fall broccoli yield and biomass. Mean total biomass (cover crop + weeds) by site year ranged from 1,890 kg ha−1 in MN Y1 to 5,793 kg ha−1 in WI Y2 and varied among species in Y1 for both the SD and LD treatments. Most cover crops did not outcompete weeds, but treatments with less weeds produced more overall biomass. Data from Y1 show that cover crops were unable to replace fertilizer for fall broccoli yield, and led to reduced fall crop yield. Broccoli in Y2 did not reach maturity due to fall freeze. Summer cover crops, because of their biomass accumulation potential, may be used by farmers in northern climates to fit into cropping system niches that have historically been left as bare soil, but care with timing is necessary to optimize weed suppression and mitigate tradeoffs for cash crop production.

Soil nitrous oxide emissions from no-till canola production under variable rate nitrogen fertilizer management

Precision farming methods such as variable rate or site-specific nitrogen (N) fertilizer application based on field management zones may represent a mechanism to mitigate soil nitrous oxide (N2O) emissions. To investigate the impact of site-specific N fertilization on soil N2O fluxes a study was conducted from spring 2013 through summer 2015 on no-till cropland under canola (Brassica napus) production near Brandon, Manitoba, Canada. The static chamber method was used to measure soil N2O fluxes across three management zones (low yield, average yield, and high yield) with three N application rates (50%, 100%, and 150% of target seed yields for each management zone) and unfertilized control treatments. A machine-learning approach (random forest analysis) for analyzing soil N2O fluxes confirmed conditions related to soil temperature, moisture, and nitrate availability were the most important predictors of individual flux events. Similarly, soil N availability and moisture content were found to be the most important variables in regression models of cumulative growing season emissions. Nitrogen fertilizer-induced N2O emission factors were lower for the high yield management zone (≈0.1% both growing seasons) compared to the low yield management zone (0.9% in 2013 and 0.2% in 2015) confirming that variable rate application can mitigate N2O fluxes from cropland soils. The high yield zones had the lowest emission factors despite receiving 50% more fertilizer than field average target yields suggesting more efficient crop N use in these areas with greater production potential. Conversely, the low yield zones had higher emission factors despite receiving 50% less fertilizer than field average target yields indicating a greater environmental burden associated with annual cropping these portions of the agricultural landscape. More studies are required to investigate the generality of these findings for different crops, soils and climatic conditions.

Assessing the Potential of Jellyfish as an Organic Soil Amendment to Enhance Seed Germination and Seedling Establishment in Sand Dune Restoration

Worldwide, sandy coastlines are affected by extensive wind and water erosion. Both soil quality and periodic drought present major problems for sand dune restoration projects. Hence, soil amendments are needed to improve soil quality and enhance soil restoration efficiency. The jellyfish population has increased in some aquatic ecosystems and is often considered as a nuisance because of their negative impacts on marine ecosystem productivity as well as coastal attractiveness. Thus, development of new products derived from jellyfish biomass has received attention from researchers although utilization is still at a preliminary stage. Herein, our main objective was to test seed germination, seedling establishment, and seedling vitality of annual ryegrass (Lolium multiflorum L.) when supplied with organic soil amendment from two different jellyfish species (Aurelia aurita and Cyanea capillata) in comparison with an unfertilized control and mineral fertilizer treatment. We hypothesized that jellyfish dry matter as an organic soil amendment would improve seed germination and seedling establishment in sand dune environments. Germination and seedling growth experiments were conducted in the laboratory and greenhouse. The results indicate that jellyfish enhanced seedling growth and establishment in sand dune soil significantly (p < 0.05 and p < 0.01) under water scarcity conditions. Therefore, jellyfish may have potential for an auxiliary role in sand dune restoration projects in coastal areas in the future.

Response of grassland vegetation composition to different fertilizer treatments recorded over ten years following 64 years of fertilizer applications in the Rengen Grassland Experiment

AbstractQuestionsFertilizer application is a key driver affecting the diversity and conservation value grassland vegetation. Using a long‐term fertilization experiment in mountain grassland, we addressed the following questions: (a) what is the effect of long‐term fertilizer applications on species richness and plant species composition, and (b) is there any detectable trend in plant species composition during ten years of continuous observation?LocationThe Rengen Grassland Experiment, Eifel Mountains, Germany (established in 1941).MethodsFive treatments including different fertilizers applied annually and one unfertilized control were analysed: Ca (718 kg Ca ha−1); CaN (752 Ca and 100 N kg ha−1); CaNP (752 Ca, 100 N and 35 P kg ha−1); CaNP‐KCl (752 Ca, 100 N, 35 P and 133 K kg ha−1); CaNP‐K2SO4 (752 Ca, 100 N, 35 P and 133 K kg ha−1). The experiment included five replicates per treatment in a fully randomized block design. All treatments were cut twice a year in late June or early July, and in mid‐October. Percentage cover of individual plant species was estimated by visual observation in each plot in late June in the years 2005–2014.ResultsDespite inter‐annual variability in the cover of the individual vascular plant species, the multivariate data analyses revealed a relatively similar response of the plant community to the different fertilizer applications throughout the ten years. With phosphorus application, no differences in botanical composition among treatments were found; however, they did differ from other treatments without phosphorus application. In the unfertilized control, there was a certain directed trend in plant species composition in response to ongoing nutrient impoverishment.ConclusionSpecies‐rich grasslands of high nature conservation value were only maintained under P limitation in the control without fertilizer application (Violion caninae) and in the liming treatment (Polygono‐Trisetion), but also in the treatment with liming and pure N addition. It seems that after 74 years, some stage of equilibrium of the grassland community was achieved in all treatments receiving any type of fertilizer application, but less so in the unfertilized control treatment.

Oilseed Rape (Brassica Napus L.) Nutrition by Nitrogen and Phosphorus and its Effect on Yield of Seed, Oil and Higher Fatty Acids Content

The effect of phosphorus (P) and nitrogen (N) application on yield, oil and fatty acids content (especially oleic acid, linoleic acid and linolenic acid) in rapeseed was investigated in the field experiment. Also effect of weather conditions was evaluated. The polyfactorial trial was realized in experimental years 2013/2014 and 2014/2015 in terms of agricultural cooperative in Mojmírovce. The experiment was based on three variants of fertilization treatments by the block method in three replications. The size of each block was created by plots with size 600 m2. The first level of treatment 10 was non-fertilized control. The second level of treatment 2U was fertilized by nitrogen in dose 240 kg.ha-1. The third level of treatment 3P was fertilized by the same dose of nitrogen 240 kg.ha-1 and by phosphorus in dose 88 kg.ha-1. The highest average yield 3.9 t.ha-1 was achieved at treatment 3P, where phosphorus was applied. It means statistically significant yield increase by 30% compared to treatment 2U, where no phosphorus was not applied. There was statistically non-significant difference in oil content, in the range of treatments. The content of oleic acid fluctuated from 63.3% to 65.9% and the highest was reached at unfertilized control treatments in both experimental years. The linoleic acid content ranged from 20.3% to 21.2% and content of linolenic acid varied between 6.9% and 8.9%. Application of nitrogen and nitrogen + phosphorus high statistically significant decreased oleic acid content in both experimental years. Opposite effect was observed, where content of linoleic and linolenic acid was high statistically significant increased after nitrogen and nitrogen-phosphorus fertilization. Effect of unequal weather conditions and treatments of nitrogen and nitrogen-phosphorus nutrition can influence the percentage ratio of higher fatty acids composition.

Foliar application of molybdenum on cover crops and response of common beans in successive cultivation

ABSTRACT The effects of foliar application of Mo and use of N from cover crops (Crotalaria juncea L. and Canavalia ensiformis (L.) DC) on the performance of common beans were investigated in this study. Field experiments were carried out in a succession planting system (cover crops - common beans), and nitrate reductase activities were evaluated in the laboratory. The production of cover crops was done in a 2 x 4 factorial scheme installed in random blocks with four replications. The two cover crops sunn hemp and jack bean composed the first factor and the molibdenum doses (0, 40, 80, and 120 g ha-1) the second. These doses were applied as foliar fertilization using sodium molybdate (Na2MoO4) as Mo source. For bean cultivation, an unfertilized control treatment was evaluated.. Sunn hemp showed a linear positive response to Mo application in terms of shoot dry matter and N accumulation, while jack bean showed a quadratic negative response for shoot dry matter; for N accumulation, there was no adjustment of the regression models. Nitrate reductase activity in the common beans was up to three times higher at the Mo dose of 0 g ha-1 when compared to the treatments with Mo application to both cover crops. Cover crops or Mo doses had no significant effect on bean productivity.

Comparison of granulated and loose ash in fertilisation of Scots pine on peatland

The effects of wood ash fertilisation on tree nutrition and growth on forested peatlands has been studied using loose ash, but in practice, ash fertilisation is done almost exclusively with granulated ash. In this study, the effects of granulated ash and loose ash (both 5 Mg ha) on the growth and nutrition of Scots pine ( L.) stands were compared between a nitrogen-poor and a nitrogen-rich site over 15 years. On the nitrogen-rich site, wood ash application was also compared with commercial PK fertilisation. On the nitrogen-rich site, mean stand volume growth increase over unfertilised control treatment during the 15 year study period using granulated ash and commercial PK fertiliser was of the same magnitude (on average, 2.2–2.3 m ha a). However, when loose ash was used growth increase over control was higher (3.7 m ha a). On the nitrogen-poor site, the mean growth increase gained by loose or granulated ash (1.4–1.5 m ha a) over the unfertilised control treatment was not significant. Fertilisation with loose ash or PK increased foliar P, K and B concentrations already in the first or second growing season, following fertilisation on both sites. Granulated ash increased foliar P concentrations on the nitrogen-rich site less than loose ash. After an initial increase, foliar P, K and B concentrations decreased at the end of study period. On the nitrogen-poor site, foliar P concentrations were below the deficiency limit by the end of the study period.–1Pinus sylvestris3–1–13–1–13–1–1

Impact of organic and mineral fertilising on aluminium mobility and extractability in two temperate Cambisols

Different fertilisation systems cause changes in the content of mobile aluminium (Al) forms in the soil as a result of soil pH changes. Long-term stationary fertilisation experiments established in 1996 at 2 sites were evaluated. Experiments consisted of unfertilised control treatment and 6 other treatments, combining mineral fertilisation with the application of farmyard manure, sewage sludge and straw. To record the changes in mobile Al forms, we used 5 extraction procedures with agents: water, CaCl<sub>2</sub>, KCl, CaCl<sub>2</sub>/DTPA (CAT) and Mehlich 3 solutions. At treatment nitrogen (N) + straw, topsoil acidification was observed, resulting in the increased content of mobile Al. At treatments with mineral fertilisation (N, NPK), increased content of mobile forms of Al was recorded. Application of cattle manure and sewage sludge helped to stabilise the soil pH and reduce mobile Al forms. The close correlation between the methods determining the exchangeable Al (CaCl<sub>2</sub> and KCl solutions) was observed; however, KCl extraction was more favourable in soils of low Al extractability, as the amount of extracted Al was 3–4 times higher. Positive correlations were determined between Al extracted by Mehlich 3 solution and the content of exchangeable Al. The less frequently used CAT method also turned out to be perspective for mobile Al determination. Furthermore, aluminium content determined in Mehlich 3 extract was compared with mobile phosphorus amounts in H<sub>2</sub>O, CAT and Mehlich 3, respectively. All three investigated phosphorus forms showed significantly negative correlations with Al.

Shoot and root production in mixed grass ley under daily fertilization and irrigation: validating the N productivity concept under field conditions

The literature suggests a linear relationship between the N supply and relative growth rate (RGR) of plants. Our objective was to evaluate this concept for a typical mixed grass-ley in Sweden under field conditions, subjected to various combinations of irrigation and N fertilization, and to assess belowground C and N allocation patterns. For that purpose, we measured aboveground biomass 30 times through two consecutive years. Environmental variables, such as soil temperature and radiation, were continuously monitored and soil mineral N concentrations were measured to 0.9 m depth at 10 occasions. During the second year, belowground biomass to 1 m depth was measured. The unfertilized and non-irrigated control treatment showed the lowest aboveground production. In this experiment, both fertilization and irrigation had significant effects on production. Growth dynamics for all growth periods and treatments was reflected by a logistic function (R2 = 0.98). RGR significantly increased with N concentration in aboveground plant tissues (R2 = 0.81), validating the nitrogen productivity concept for a forage crop under field conditions. Living root biomass (247–330 g m−2) was mainly (83–92%) located in the upper 0.30 m under all treatments. Generally, the shoot-to-root ratios (0.58–2.67) and N concentrations in living roots increased with irrigation and N fertilization. Soil profiles of mineral N gave no clear indications of environmental risks. Supplementary materials provide the detailed dataset useful for crop growth modelling purposes.

The effect of anaerobic digestate derived composts on the metabolite composition and thermal behaviour of rosemary

The study reports on the effect of anaerobic digestate derived composts on the metabolite composition and thermal behaviour of rosemary (Rosmarinus officinalis L.). Plants were cultivated in semiarid soil under four different fertiliser treatments (composts of anaerobic digested cattle (C) or pig slurry (P) at 30t/ha and 60 t/ha, and two control treatments (inorganic fertiliser and no fertiliser application). Samples of leaves and stems were analysed to investigate the effect of treatment on chemical composition and thermochemical properties. Three orthogonal analytical approaches were used, namely: Fourier transform mid infrared spectroscopy (FTIR), gas chromatography/mass spectrometry (GC/MS) and thermochemical gravimetric analysis (TGA). FTIR and GC/MS showed fertiliser treatment resulted in tissue specific changes in sample metabolite composition. Fertiliser treatment was detected to change the thermogravimetric properties of the leaf samples and from inorganic and composted pig slurry digestate treatments had greater ash content and lower proportions of fixed carbon compared with samples from the unfertilised control treatment. This study provides information on how the composition of rosemary might be altered by fertiliser application in regions of poor soil, and has implications for biomass quality when rosemary is grown on semi-wild sites for the purpose of soil improvement.

Comparative effect of alternative fertilisers on pasture production, soil properties and soil microbial community structure

Different fertiliser products are commonly promoted for use on pastures in order to improve pasture productivity and support a more ‘healthy’ soil microbial environment. However, minimal field research has been conducted to validate such claims. A 6-year study (2009–14) was conducted on phosphorus (P)-deficient soils at three sites near Yass, New South Wales, to investigate the effect of topdressing perennial native-based pastures with a range of alternative fertilisers compared with single superphosphate and an unfertilised control treatment. The alternative fertiliser products included manures, composts, crushed rock, rock-phosphate-derived products, concentrated ash and microbial products. Annual measurements were made of soil chemical properties, botanical composition and pasture yield during spring and/or winter + spring, as well as the relative effectiveness of products per unit of pasture grown. Soil microbial community structure under each fertiliser treatment was also analysed in the sixth year of the study. Fertiliser products with substantial quantities of P increased extractable soil P and resulted in significantly higher pasture growth and clover content compared with the unfertilised control. Superphosphate was found to be the most P-effective fertiliser for increasing pasture growth, along with a range of other products that showed differential responses. However, the cost and P-effectiveness of the products in relation to pasture growth varied considerably and was a function of rate and frequency of application as well as amount and solubility of the P applied. Despite large differences in pasture growth across the various fertiliser treatments, there was no significant effect of the alternative fertiliser products on microbial community structure compared with either the superphosphate or unfertilised control treatments. The observed variation in bacterial, fungal and archaeal community structures across all fertiliser treatments was best explained by soil pH or aluminium (Al) concentration, which was influenced differentially by the fertiliser products. Fungal community structure was also correlated with pasture-productivity parameters (i.e. spring pasture yield, clover content and soil-available P). Our findings reveal a highly resilient soil microbial community that was influenced minimally by use of the alternative fertiliser products, thus highlighting that on-farm management decisions regarding fertiliser product choice should primarily focus on pasture response and cost-effectiveness.