Compost Incorporation Research Articles

Enhancing Soil Quality through Residue Management in a Rice-Wheat System in Fukuoka, Japan

A long-term experiment (LTE) on a rice-wheat system was initiated in 1963 at the Kyushu National Agricultural Experiment Station, in Fukuoka, Japan, to determine the effects of continuous application of rye grass/wheat straw, rice straw and rice straw compost, alone or in combination with inorganic N on crop yields. Increase in rice yields and enhancement of total soil C and N contents with the application of organic residues in this LTE have been reported earlier. However, evaluation of the changes in the soil microbiological properties and the decomposable C fraction of soil organic matter that is needed for soil quality assessment is still lacking. Soil samples were collected after rice harvest in 2003 from the organic residue treatments and unfertilized control, air-dried and incubated for 1 month under aerobic [50% water-filled pore space (WFPS)] and flooded conditions prior to the analysis of the amount of microbial biomass C (MBC), soil respiration and the amount of potential mineralizable N (PMN). The contents of total C (TC), total N (TN), organic C (OC), hot water-extractable C (HWEC) and permanganate-oxidizable C (POC) were determined from air-dried soils. Organic residue incorporation brought about significant increases in the contents of TC, TN, OC, POC, HWEC and PMN. The largest accumulation of total C (23%) and N (72%) in the soil was from rice straw compost, compared with that from rice straw (C, 7% and N, 33%) and rye grass/wheat straw (C, 9% and N, 29%). Incorporation of rice straw compost also increased the amount of MBC under both aerobic and flooded conditions and basal soil respiration under aerobic conditions only. An efficient utilization of C by microorganisms was indicated by a significantly lower metabolic quotient (qCO2) in the composted and uncomposted rice straw treatments compared with the control in the “-” N treatment under aerobic conditions. Similarly, the flush of CO2 after rewetting of dry soil per unit of HWEC was lower in the organic matter treatments, indicating a more efficient C utilization and lower C losses per unit of available C. The content of HWEC was significantly correlated with the basal soil respiration (at 50% WFPS), the amounts of MBC, PMN and with the increase in the content of soil organic C in the residuetreated soils. In the treatments without inorganic N fertilizer, grain yield was significantly correlated with the amounts of total organic C, HWEC, MBC (at 50% WFPS), basal soil respiration (at 50% WFPS) and the amount of PMN.

Fertilizer Applications on Establishment and Growth of Three Groundcover Species in Sun and Shade

Abstract Use of groundcovers in the landscape is often limited by slow establishment when compared to turf. Hedera helix L. (English ivy), Euonymus fortunei ‘Coloratus’ (Turcz.) Hand.-Mazz. (purpleleaf wintercreeper euonymus) and Liriope spicata Lour. (creeping lily-turf) were evaluated in full sun and 60% shade to determine the effects of fertilizer applications on establishment and growth. Limited fertilizer × species interaction was detected, which may have been due, in part, to the soil incorporation of mushroom compost. Establishment and survivability of Hedera in full sun may have been influenced by lack of acclimation from shade to sun. There was no significant difference in establishment rates between Liriope and Euonymus; however, under shade Euonymus did not develop its characteristic fall color. Hedera was established in one season under 60% shade and, of these three species, can be considered the most competitive with turf under similar conditions for low traffic areas of the landscape.

(57) Bioassays and Small-scale Greenhouse Experiments Conducted to Evaluate the Suppression of Phytophthora cinnamomi Activity on Rhododendron × PJM `Elite' by Different Composts Incorporated into Growing Media

Composts vary in their ability to suppress disease activity when incorporated into growing media. Bioassays that enable a reliable and quick assessment of compost's ability to suppress disease activity can save time, funds and space. A bioassay using Lupinu× `Russell Hybrid' seedlings was evaluated as a short-term test for gauging the ability of three composts to suppress activity of P. cinnamomi. Colonized millet seeds were prepared via the V-8 agar method. The colonized millet seed were incorporated into the potting media at 0, 50, 100, 200, and 400 colonized millet seed/200 cc of the media used. Three composts, including composted sewage sludge, brewer's waste and cow manure, were incorporated into the media (50% sand: 50% sphagnum peat, by volume) at rates of 0%, 10%, 25%, and 50%, by volume. The media, including the inoculated millet seed, were placed in small plastic pots (7.6-cm-diameter and 6.7 cm high), after which 10 Lupine seeds were sowed in each pot. Percentage of seedling loss was determined after 43 days of observation. The composted sewage sludge and the cow manure proved suppressive at the 50% incorporation rate and the 10% and 25% rate of the latter compost. The brewer's waste compost proved ineffective in this regard; thus, research with this product was discontinued. In a greenhouse study the same inoculation and compost incorporation rates were used, but rooted cuttings of Rhododendro × PJM `Elite' were plotted into the various treatments. Suppression of disease activity by the composts was significant 2 and 4 months after initiation of treatments. Significance in disease suppression noted between these treatments decreased significantly during the fifth month of the experiment.

Solubility of phosphorus and heavy metals in potting media amended with yard waste-biosolids compost.

The potential risk of surface and ground water contamination by phosphorus (P) and heavy metals leached from compost-based containerized media has become an environmental concern. Solubility and fractionation of P and heavy metals were evaluated in media containing 0, 25, 50, 75, or 100% compost derived from biosolids and yard trimmings for potential impacts on the environment. As compost proportion in peat-based media increased from 0 to 100%, concentrations of total P, Cd, Cu, Ni, Pb, Zn, and Mn in the media increased whereas concentrations of total Co and Cr decreased. Except for Cu, all heavy metals in the water-soluble fraction decreased with increasing compost proportion in the media, because of higher Fe, Al, and Ca concentrations and pH values of the composts than the peat. When the media pH is controlled and maintained at normal range of plant growth (5.5-6.5), leaching of the heavy metals is minimal. Incorporation of compost to the peat-based media also decreased the proportion of total P that was water-soluble. However, concentrations of bioavailable inorganic phosphorus (NaHCO3-IP), readily mineralizable organic phosphorus (NaHCO3-OP), potentially bioavailable inorganic phosphorus (NaOH-IP), and potentially bioavailable organic phosphorus (NaOH-OP) were still higher in the media amended with compost because of higher total P concentration in the compost. Further study is needed to verify if less or no topdressing of chemical P fertilizer should be applied to the compost-amended media to minimize P effect on the environment when compost-amended potting media are used for nursery or greenhouse crop production systems.

Compost mineralization in soil as a function of composting process conditions

Compost has been shown to have a range of positive impacts on soil quality and can provide an important source of nutrients for plants. While these benefits have been documented for many finished composts, there is presently little understanding of the impact of composting process conditions and the extent of compost decomposition on soil C and N mineralization after compost incorporation. This study evaluated the impact of composting process conditions and the extent of compost decomposition on soil C and N mineralization after compost incorporation. Dried, ground composts were blended with equal parts of quartz sand and soil and incubated aerobically for 28 d at 30 °C. Cumulative respired CO 2–C and net mineralized N were quantified. Results indicate that (1) organic substrates that did not degrade due to sub-optimal conditions during the composting process can readily mineralize after incorporation in soil; (2) C and N cycling dynamics in soil after compost incorporation can be affected by compost feedstock, processing conditions, and time; and (3) denitrification after compost incorporation in soil can limit N availability from compost.

Nitrogen Availability Seven Years After a High-Rate Food Waste Compost Application

Long-term effects of compost application are expected, but rarely measured. A 7-yr growth trial was conducted to determine nitrogen availability following a one-time compost application. Six food waste composts were produced in a pilot-scale project using two composting methods (aerated static pile and aerated, turned windrow), and three bulking agents (yard trimmings, yard trimmings + mixed paper waste, and wood waste + sawdust). For the growth trial, composts were incorporated into the top 8 to 10 cm of a sandy loam soil at application rates of approximately 155 Mg ha−1 (about 7 yd3 1000 ft2). Tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’) was seeded after compost incorporation, and was harvested 40 times over a 7-yr period. Grass yield and grass N uptake for the compost treatments was greater than that produced without compost at the same fertilizer N rate. The one-time compost application increased grass N uptake by a total of 294 to 527 kg ha−1 during the 7-yr. field experiment. The greatest grass yield response to compost application occurred during the second and third years after compost application, when annual grass N uptake was increased by 93 to 114 kg ha−1 yr−1. Grass yield response to the one-time compost application continued at about the same level for Years 4 through 7, increasing grass N uptake by 42 to 62 kg ha−1 yr−1. Soil mineralizable N tests done at 3 and 6 yr. after application also demonstrated higher N availability with compost. The increase in grass N uptake accounted for 15 to 20% of compost N applied after 7-yr. for food waste composts produced with any of the bulking agents. After 7-yr, increased soil organic matter (total soil C and N) in the compost-amended soil accounted for approximately 18% of compost-C and 33% of compost-N applied. This study confirmed the long-term value of compost amendment for supplying slow-release N for crop growth.

Soil Physical Conditions and Physiological Performance of Cowpea Following Organic Matter Amelioration of Sandy Substrates

Mulch was added to sand and sandy loam soil in order to simulate repeated additions of organic matter into soils of the tropics where high temperatures cause rapid decomposition. The experiments used pots (0.003 m3) and lysimeters (0.18 m3) to investigate the effect of farmyard manure (FYM) and municipal waste compost (MWC) incorporation on temperature, soil water retention and evaporation, and MWC on transpiration, photosynthetic rate and yield as performance indicators for cowpea [Vigna unguiculata (L)]. Incorporation of FYM and MWC in un-cropped pots increased early stage evaporation compared with surface mulch treatments and compost mulch conserved soil water at depths between 0.05 and 0.6 m. Repeated incorporation of compost in lysimeters increased crop water availability between 7 and 10% and yield increased 3 to 5 times, despite organic matter content remaining below 1%. Results show cowpea performance indicators in light, low fertility soils of the tropics would benefit substantially from repeated incorporations of compost.

Preplant Monoammonium Phosphate Fertilizer and Compost Affects the Growth of Newly Planted 'Macoun' Apple Trees

'Macoun'/Budagovsky 9 apple (Malus ×domestica Borkh.) trees were planted in May 1998 in one of four preplant treatments that were soil incorporation of: 1) control, no phosphorus (P); 2) 90 g P per tree; 3) 128 kg compost per tree; and 4) 90 g P and 128 kg compost per tree. Preplant addition of P had no effect on soil organic matter, P, magnesium (Mg), and calcium (Ca) in the first three seasons after planting, but lowered soil potassium (K) in the second season. Foliar nutrients, tree growth and flowering were also not affected by P. The addition of compost increased soil organic matter and P in the first season after planting, and pH, K, Mg, and Ca in the first three seasons. The addition of compost increased foliar nitrogen and K in all three seasons, and decreased foliar Mg in the first season. Compost incorporation increased shoot length in the first season, trunk cross-sectional area in the first two seasons, tree height and the number of growing points in third season, and flowering in the third and fourth seasons. Compost addition was more effective than P fertilization for increasing tree growth during the establishment years.

Soil microbial activity after restoration of a semiarid soil by organic amendments

Unsuitable agricultural practices together with adverse environmental conditions have led to degradation of soil in many Mediterranean areas. One method for recovering degraded soils in semiarid regions, is to add organic matter in order to improve soil characteristics, thereby enhancing biogeochemical nutrient cycles. In this study, the effect of adding the organic fraction of urban wastes (both fresh and composted) on different carbon fractions and on microbiological and biochemical parameters (microbial biomass C, basal respiration and different enzymatic activities) of a degraded soil of SE Spain has been assessed in a 2 year experiment. Three months after the addition of the organic material, spontaneous plant growth occurred and the plant cover lasted until the end of the experiment. Organic soil amendment initially increased the levels of soil organic matter, microbial biomass, basal respiration and some enzyme activities related to the C and N cycles These values decreased but always remained higher than those of the unamended soil. The results indicate that the addition of urban organic waste is beneficial for recovering degraded soils, the microbial activity of which clearly increases with amendment. The incorporation of compost seemed to have a greater positive effect on the soil characteristics studied than the incorporation of fresh organic matter.

Effects of red clover ( Trifolium pratense ) green manure and compost soil amendments on wild mustard ( Brassica kaber ) growth and incidence of disease

Using a soil bioassay technique, seedling growth and incidence of disease of wild mustard (Brassica kaber) and sweet corn (Zea mays) were assessed in soil from field plots that received either of two treatments: incorporated red clover (Trifolium pratense) residue plus application of compost (`amended soil'), or application of ammonium nitrate fertilizer (`unamended soil'). Soils were analyzed for percent moisture, dissolved organic carbon, conductivity, phenolics, and nutrient content. A trend toward greater incidence of Pythium spp. infection of wild mustard seedlings grown in amended soil was observed during the first 40 days after incorporation (DAI) of red clover and compost, with significant differences (α = 0.05) at two out of four sampling dates in 1997, and four out of four sampling dates in 1998. Incidence of Pythium infection was 10–70% greater in the amended soil treatment during that period. Asymptomatic wild mustard seedlings grown in amended soil were also on average 2.5 cm shorter (α = 0.05) at 5 DAI than those grown in unamended soil in one year out of two. Concentration of phenolic compounds in soil solution was weakly correlated with decreased shoot and root growth (r = 0.50, 0.28, respectively) and increased incidence of disease (r = 0.48) in wild mustard seedlings in one year out of two. Dissolved organic carbon concentration was weakly correlated with increased disease in wild mustard seedlings in both years (r = 0.51, 0.33, respectively). Growth of corn seedlings did not differ between the two soil treatments, suggesting that red clover green manure and compost may selectively reduce density and competitive ability of wild mustard in the field. Bioassay results corresponded well with emergence and shoot weight results from a related field study, indicating that this technique may be useful for screening potential soil treatments prior to field studies.

Yard Waste Compost as a Landscape Soil Amendment for Azaleas

Abstract Azaleas, Rhododendron indicum L. ‘G.G. Gerbing’, were transplanted into landscape beds amended with yard waste compost at rates of 0, 5.1, 7.6, or 10.2 cm (0, 2, 3, or 4 in) incorporated into the top 18 cm (7 in) of a sandy soil. Plants were irrigated on alternate days (high irrigation rate) or on every third day (low irrigation rate), and shoot and root growth measurements were recorded at 0, 4, 8, 12, and 18 months after transplanting. Differences among compost treatments for plant quality and root elongation were observed after 8 months. By 18 months, incorporation of 7.6 or 10.2 cm (3 or 4 in) of compost resulted in plants with larger shoots, greater root, elongation, and larger root masses compared to the 0 and 5.1 cm (2 in) compost treatments. The larger azalea shoots and roots achieved with high rates of compost occurred under both irrigation regimes. Incorporating 7.6 or 10.2 cm (3 or 4 in) of compost increased root elongation, mostly between 4 and 8 months, and increased root mass after 12 months. Compost incorporation affected the quality of plants under high irrigation, with 10.2 cm (4 in) of compost producing the highest-quality plants.

Composted Biosolids Incorporation Improves Turfgrass Establishment on Disturbed Urban Soil and Reduces Leaf Rust Severity

The effects of incorporation of compost to a disturbed urban soil on turfgrass establishment, growth, and rust severity were assessed in a replicated field study. A blend of two locally available composted biosolids (sewage sludge) was incorporated into a nutrient-deficient subsoil at a rate of 130 m3·ha-1, adding NO3-N, P, and K at 126, 546, and 182 kg·ha-1, respectively, to each compost-amended plot. Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and a mixture of these two species were seeded into both compost-amended and nonamended plots and observed for 1 year. Turfgrass establishment estimated from visual assessments of percentage cover and growth measured by clipping yields were significantly (P < 0.05) enhanced by the incorporation of the composted biosolids. These effects were first observed and most pronounced on plots seeded with perennial ryegrass and were apparent for the duration of the study. The severity of leaf rust caused by Puccinia sp. was significantly (P < 0.05) less on perennial ryegrass seeded on the compost-amended plots. This study demonstrates the feasibility and potential benefits of amending disturbed urban soils with composted biosolids to enhance turfgrass establishment and is the first report of the suppression of a foliar turfgrass disease through the incorporation of compost into soil.

Methane Emission from Deepwater Rice Fields in Thailand

Field experiments were conducted in the Prachinburi Rice Research Center (Thailand) from 1994 to 1998. The major objective was to study methane (CH4) emission from deepwater rice as affected by different crop management. Irrigated rice was investigated in adjacent plots, mainly for comparison purposes. The 4-yr average in CH4 emission from deepwater rice with straw ash (burned straw) treatment was 46 mg m−2d−1 and total emission was 98 kg ha−1 yr−1. For irrigated rice, the average emission rate and total emission for the straw ash treatment was 79 mg m−2 d−1 and 74 kg ha−1 yr−1, respectively. Low emission rates may partially be related to acid sulfate soil of the experimental site. Without organic amendment, the seasonal pattern of CH4 emission from deepwater rice was correlated with an increase in biomass of rice plants. Emission rates from deepwater rice depend on the production of biomass and the straw management as well. Methane emission was greatest with straw incorporation, followed by straw compost incorporation, zero-tillage with straw mulching, and least with straw ash incorporation. The seasonal pattern of CH4 ebullition in deepwater rice was consistent with seasonal emission, and total ebullition corresponded to 50% of total emission. Dissolved CH4 concentrations in the surface soil (0–5 cm) were similar to those in the subsoil (5–15 cm), and the seasonal fluctuation of dissolved CH4 was also consistent with the seasonal CH4 emission. Increase in plant density and biomass of irrigated rice grown by pregerminated seed broadcasting enhanced CH4 emission as compared with transplanting.

600 The Effect of Weed Control Methods on Soil Physical Properties and Plant Growth

There has been recent speculation in trade journals that landscape fabrics, while doing an excellent job of weed control, may have a detrimental effect on ornamental plant growth. A study is in progress to investigate the manner in which hardwood mulch and applied landscape fabric affect soil temperature, soil aeration, and water content over 18 months. Two experiments are in progress, one with compost incorporated at 50% soil volume, the other with no compost incorporation. The experimental design is a randomized complete block with four treatments (mulch, fabric, fabric plus mulch, and control) and four plants per plot. Each plot has been planted with herbaceous perennials so as to allow analysis of treatment effects on plant growth. Soil temperature within plots is monitored on a continual basis. Soil aeration is measured every two weeks using installed oxygen tubes. Water content is measured using time domain reflectometry 24 and 48 h after a significant rainfall event. Preliminary results suggest that hardwood mulch and landscape fabric are similar in their effect on soil water content 0 to 48 h after a significant rainfall event. However, after 48 h, hardwood mulch increases soil water retention compared to landscape fabric.

Effects of a cadmium-contaminated sewage sludge compost on dynamics of organic matter and microbial activity in an arid soil

An incubation experiment lasting 120 days was carried out to ascertain the effect on the soil microbial activity and organic matter mineralization of adding a sewage sludge compost contaminated with two different levels of Cd to an arid soil. Two composts, with a low (2 mg kg–1) and high (815 mg kg–1) Cd content, respectively, were used in this experiment. Both composts increased the total organic C, humic substance and water-soluble C contents, the beneficial effects still being noticeable after 120 days of incubation. The most labile C fraction (water-soluble C) was the most sensitive to the high Cd content. The high Cd concentration decreased soil microbial biomass C and stimulated the metabolic activity of the microbial biomass, the metabolic quotient (qCO2) revealing itself to be a very sensitive index of the stress that the incorporation of a Cd-contaminated sewage sludge compost causes in a soil. The effect of Cd contamination on enzyme activities (urease, protease that hydrolyse N-α-benzoil-l-arginamide, phosphatase, and β-glucosidase) depended on the enzyme studied.

Heterogeneidade do solo sob diferentes adubações na cultura do milho

A partir dos dados de um experimento bifatorial em parcelas subdivididas no delineamento inteiramente casualidade, com três formas de adubação nas parcelas principais, e com duas cultivares de milho, com 10 repetições (20 subparcelas), foram estudados: a variabilidade entre as subparcelas agrupadas em diferentes tamanhos, após subtrair-se o efeito da causa de variação cultivar; e o índice de heterogeneidade do solo para cada repetição das formas de adubação. Estas consistiram em: FA1 - adubação recomendada para rendimento de grãos menor do que 3,0t/ha; FA2 - adubação recomendada para rendimento maior do que 6,0t/ha e tratamento das sementes com Zn; e FA3 - igual a FA2, mais a incorporação ao solo de um composto orgânico. Analisando a variância dos diferentes tamanhos de parcela, observou-se uma relação entre o tamanho da parcela e a forma de adubação, sendo que, para o menor tamanho (5m²) a FA1 apresentou a menor variância, e para o maior tamanho (25m² ), não houve diferença significativa entre as adubações. Pela estimativa do índice de heterogeneidade do solo das formas de adubação, conclui-se que a inclusão do adubo orgânico intensifica a variabilidade existente no solo, quando comparado com adubos químicos.

COMPOSTED ORGANIC RESIDUES AS A SUBSTRATE COMPONENT FOR TOMATO TRANSPLANT PRODUCTION

Pine bark and grape marc composts were tested in the production of tomato seedlings as substrate components after composting in 1.2 m 3 boxes. The composting process of pine bark took 20 weeks with a low temperature increase. Grape marc composting process took 16 weeks, reaching a higher temperature. Composts were used as single substrate components and in mixtures with a sphagnum peat, in the proportions of 25, 50 and 75% (v/v) of compost. Tomato seeds were seeded in modular trays of 35 cm 3 and irrigated by “ebb and flood” irrigation system. The growth of tomato plants in the mixtures was similar or better than in a standard peat substrate, mainly in the first year of trials. Pine bark performed generally better than grape marc. Plant growth was significantly correlated with the physical properties of the substrates mainly in grape marc mixtures and in the trials under higher levels of radiation. A higher incorporation of compost determines a lower water retention capacity and a poor performance of the mix. Good tomato seedlings growth was possible using mixtures with an incorporation of composts reaching 100% of pine bark and 50% of grape marc.

Determinants of Soil Microbial Communities: Effects of Agricultural Management, Season, and Soil Type on Phospholipid Fatty Acid Profiles

Phospholipid fatty acid (PLFA) profiles were measured in soils from organic, low-input, and conventional farming systems that are part of the long term Sustainable Agriculture Farming Systems (SAFS) Project. The farming systems differ in whether their source of fertilizer is mineral or organic, and in whether a winter cover crop is grown. Sustained increases in microbial biomass resulting from high organic matter inputs have been observed in the organic and low-input systems. PLFA profiles were compared to ascertain whether previously observed changes in biomass were accompanied by a change in the composition of the microbial community. In addition, the relative importance of environmental variables on PLFA profiles was determined. Redundancy analysis ordination showed that PLFA profiles from organic and conventional systems were significantly different from April to July. On ordination plots, PLFA profiles from the low-input system fell between organic and conventional systems on most sample dates. A group of fatty acids (i14:0, a15:0, 16:1ω7c, 16:1ω5c, 14:0, and 18:2ω6c) was enriched in the organic plots throughout the sampling period, and another group (10Me16:0, 2OH 16:1 and 10Me17:0) was consistently lower in relative abundance in the organic system. In addition, another group (15:0, a17:0, i16:0, 17:0, and 10Me18:0) was enriched over the short term in the organic plots after compost incorporation. The relative importance of various environmental variables in governing the composition of microbial communities could be ranked in the order: soil type > time > specific farming operation (e.g., cover crop incorporation or sidedressing with mineral fertilizer) > management system > spatial variation in the field. Measures of the microbial community and soil properties (including microbial biomass carbon and nitrogen, substrate induced respiration, basal respiration, potentially mineralizable nitrogen, soil nitrate and ammonium, and soil moisture) were seldom associated with the variation in the PLFA profiles.

Fertilizer Nitrogen Replacement Value of Food Residuals Composted with Yard Trimmings, Paper or Wood Wastes

Composting offers an opportunity to recycle food waste as a soil amendment. A three year growth trial was conducted to determine the fertilizer nitrogen (N) replacement value of food waste composts for cool season perennial grass production. Six composts were produced in a pilot-scale project with two composting methods (aerated static pile and aerated, turned windrow). The aerated, turned windrow method simulated “agitated bay” composting systems, which utilize routine mechanical agitation. Compost bulking agents included yard trimmings, yard trimmings + mixed paper waste, and wood waste + sawdust. Finished composts had Kjeldahl N concentrations ranging from 10 to 18 g N/kg. For the growth trial, composts were incorporated into the top eight to 10 cm of a sandy loam soil at application rates of approximately 155 Mg/ha (about 7 yd3/1000 ft2). Tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’) was seeded after compost incorporation, and was harvested repeatedly at a late vegetative growth stage (April to November; approx. 35 days regrowth between harvests). Grass yield and grass N uptake did not respond to compost application during the first year. During the second and third years after application, composts were a consistent source of slow-release N. They supplied the fertilizer N equivalent of 0.70 kg N/ha/day over a 140-day period (April to August) in both years. The N supplied by composts in the second and third year after application was valued at $0.70 to $1.90 per dry tonne (Mg) compost per year, using a fertilizer N cost of $1/kg N. Food waste composts with significant slow-release N properties were produced with either the aerated static pile composting method or the aerated, turned windrow method. Composts with higher N concentrations had higher fertilizer N replacement value. The slow release N supplied by food waste composts is ideally suited for urban landscapes, where a moderate, consistent rate of plant growth is highly desirable.

Establishment of a non-dormant blueberry (Vaccinium corymbosum hybrid) production system in a warm winter climate

Summary‘Gulf Coast’, ‘Sharpblue’, and ‘Wannabe’ southern highbush blueberry (Vaccinium corymbosum interspecific hybrid) cultivars were planted at a density of 10,000 plants per ha in southwest Florida to test the feasibility of a non-dormant blueberry production system. A non-dormant production system involves application of nitrogen (N) throughout the fall and winter, which enables the plants to avoid the normal dormancy cycle and the concomitant chilling requirement. If successful, this system could extend the production range of blueberry into subtropical and tropical areas where chilling temperatures are inadequate for traditional (dormant) production systems. Nitrogen fertilizer rate (84 to 252 kg ha–1 N in year 1, 168 to 336 kg ha–1 N in year 2) was evaluated for effects on maintaining plant growth and development in this system. Additionally, since organic soil amendments are known to improve blueberry growth, the effects of municipal solid waste (MSW) compost and acidic peat on maintaining growth were also evaluated. In general, increasing N rates from 84 to 252 kg ha–1 (year 1) or 168 to 252 kg ha–1 (year 2) increased plant canopy volume, leaf retention, and rate of new vegetative budbreak. There was no consistent effect of N rates on soil nutrient concentrations, but leaf N increased and leaf Ca decreased as N rate increased. MSW compost incorporation increased P, Ca, Mg, Cu, Fe, Mn, and Zn soil concentrations compared with peat, but had no consistent effect on leaf nutrient concentrations. Plant height and canopy volume were consistently greater for plants grown in the MSW compost compared with the peat amendment, but there were no differences in leaf retention or vegetative budbreak between the two soil amendments. Plants in this non-dormant system have shown no deleterious growth effects, suggesting that establishing a blueberry planting in a warm winter climate is feasible under the described conditions.