Compost Application Rates Research Articles

Impact of short-term organic amendments incorporation on soil structure and hydrology in semiarid agricultural lands

Soil structure plays an important role in edaphic conditions and the environment. In this study, we investigated the effects of organic amendment on soil structure and hydraulic properties. A corn field in a semiarid land was separately amended with sheep manure compost at five different rates (2, 4, 6, 8 and 10 t/ha) and corn stover (6 t/ha) in combination with two decomposing agents. The soil structure of different amended soils was analyzed from the aggregate and pore domain perspectives. The internal pore structure of the soil was visualized through X-ray computed tomography and quantified using a pore-network model. Soil aggregate-size distribution and stability, saturated hydraulic conductivity, and water-retention curves were measured by sampling or in situ. The gas permeability and diffusivity of different amended soils were simulated based on the extracted pore networks. The aggregate stability of the amended soils was improved compared with the control, that is, the mean weight diameter increased and the percentage of aggregate destruction decreased. The stability of soil aggregates varied non-monotonically with the application rate of compost and decreased after treatment with corn stover and decomposing agents. The pore-network parameters including air-filled porosity, pore radius, throat length, and coordinate number increased for the amended soils compared with the control. The mean pore size increased with increasing compost incorporation rate. The saturated hydraulic conductivity of the compost-amended soils was higher than that of the control but varied quadratically with the application rate. The saturated hydraulic conductivity of soil treated with corn stover and decomposing agents was clearly higher than that without the agent and the control. The greater gas diffusivity and air permeability indicate that soil aeration improved following the incorporation of organic amendments. The air permeability versus air-filled porosity relationship followed a power law, and the gas diffusivity versus air-filled porosity relationship was characterized by a generalized density-corrected model regardless of amendment. The findings of this study can help improve the understanding of soil structure and hydrological function to organic fertilizer incorporation and further monitor the quality of soil structure through the pore space perspective.

Carbon Dynamics of Fruit and Vegetable Wastes and Biodegradable Municipal Waste Compost-Amended Oxisol

Recycling of wastes via composting is advocated as a means to reduce environmental hazards due to the dumping of wastes. Composting also creates a vital source of organic matter that is important in nutrient and soil moisture retention, soil fertility preservation and improving the physical and chemical properties of soils. This study was conducted to evaluate the short-term effects of four compost amendments in an Oxisol on carbon dynamics (carbon dioxide evolution and carbon transformation). The composts were prepared in 3:1 and 1:2 of fruit and vegetable waste (FVW) to biodegradable municipal waste (BMW) with and without indigenous microorganisms (IMO) (3:1 +IMO, 1:2 +IMO, 3:1 −IMO, 1:2 −IMO). Soil incubation studies were carried out for 35 days at three compost application rates of 0, 5 and 10 Mg ha−1, with measurements done including the CO2 evolution, dehydrogenase enzyme (DHA) assay and compost Fourier transform infrared (FTIR) spectroscopy spectral analysis. At 10 Mg ha−1 compost application rate, increased soil respiration rate was obtained at 3:1 +IMO compost, mostly due to increased labile organic matter and higher amount of FVW in the compost mixture, which stimulated soil microorganisms and/or their activities reflected by increased evolution of CO2 in the process of decomposition of the added composts in the compost-amended soils. The DHA activity increased with compost application rates, and significantly, the highest DHA activity was recorded at 3:1 +IMO compost applied at 10 Mg ha−1 soil at 1.38 triphenylformazan (TPF)/g dry soil/24 h. The compost FTIR spectral analysis showed transformations that occurred due to the composting that was carried out. A broadband between 3279–3347 cm wavelength in the FTIR spectroscopy indicated the presence of carboxylic and hydroxyl functional groups because of carbon transformation that occurred in the composts.

KANDUNGAN NITRAT DAUN, PERTUMBUHAN, DAN HASIL BIOMASSA SAWI DAN PAKCOY PADA PEMBERIAN PUPUK NITROGEN ANORGANIK DAN KOMPOS AZOLLA SECARA BERIMBANG

[LEAF NITRATE CONTENT, GROWTH, AND BIOMASS YIELD OF GREEN MUSTARD AND CHINESE CABBAGE FOLLOWING BALANCED APPLICATION OF INORGANIC NITROGEN FERTILIZER AND AZOLLA COMPOST]. The aim of this study was to determine the application rate of Azolla compost, either alone or combined with inorganic N fertilizers, to produce high biomass of mustard greens and Chinese cabbage with low leaf nitrate content. The pot experiments were carried out at the Research Plot of the Faculty of Agriculture located in Bengkulu University Campus from December 2019 to January 2020 with five treatments arranged in a completely randomized design with five replications. The treatments were 100% IF or IF100 (42.0 mg N/kg soil), 100% AC or AC100 (4000 mg/kg soil), IF75 (31.0 mg N/kg soil) + AC25 (1000 mg/kg soil), IF50 (21.0 mg/kg soil) + AC50 (2000 mg/kg soil), and IF25 (10.5 mg/kg soil) +AC75 (3000 mg/kg soil). The results showed that partial replacement of IF with AC (IF75 +AC25) produced plant growth and biomass yield similar to IF100 or higher than IF100 and AC100. The treatment produced plant biomass of 9.35 g plant-1 for green mustard and 167.10 g plant-1 for pakcoy, 32% and 35% higher than AC100 treatment respectively. The leaf nitrate content was 1080 - 2760 mg kg-1 for green mustard and 2310 - 2820 mg kg-1for Chinese cabbage, lower than the maximum limit of safe nitrate for consumption which was set at 3100 mg kg-1. Overall, compared with their sole applications, the partial substitution of inorganic N fertilizer with Azolla compost represents the most effective practice to promote the biomass yield of low-nitrate green mustard and Chinese cabbage.

Growth Quality and Bioactive Compounds of Poplar Seedlings as Affected by Different Fertilization Treatments

Pot experiments were conducted during two successive seasons of 2019 and 2020 at the Fac. of Agric., Minia Univ. to investigate effects of four application rates of compost (0, 1, 2 and 3%) (w/w) and six treatments of bio-fertilizers and/or mineral NPK fertilization (control, Azotobacter chroococcum + Bacillus circulans, Azotobacter chroococcum + Bacillus megaterium, mixture of bio., mixture of bio. + 75% NPK and 100% NPK) on vegetative criteria, accumulation of bioactive compounds (phenolic compounds and flavonoids) through improving plant's secondary metabolism and antimicrobial activity of methanolic and ethanolic extracts of Populus alba. All compost treatments significantly improved all transplant vegetative growth parameters such as plant height, diameter, aerial part fresh and dry weights, main root length and roots fresh and dry weights, as well as, total chlorophylls and NPK% as compared to control. Biofertilizers and/or mineral NPK fertilization treatments significantly increased all the previous traits, the mixture of three species of bacteria plus 75% NPK followed by mineral full dose of NPK treatments were the most effective than other used treatments. The highest values were obtained when Populus alba transplants were grown in sandy soil contained 3% compost plus inoculation with three species of bacteria plus 75% NPK or compost at 3% plus 100 % NPK and these two treatments give the highest values of phenolic compounds in the methanolic and ethanolic extracts. This research confirmed that poplar is a promising wooden tree to be grown on sandy soils for timber production in Egypt, woody products and bioactive compounds.

Phytoaccumulation of Cadmium in Leafy Vegetables Grown in Contaminated Soil under Varying Rates of Compost and Phosphate Fertilizer Application

ABSTRACT Cadmium (Cd) contamination in agricultural soil is a global issue of concern because of its potential transfer to the human body through food chain interactions. Phosphate fertilizers used in the agricultural soils contain a high concentration of Cd. Composts are good sources of phosphorus, thus mixing of compost with phosphate fertilizer could reduce the total phosphate fertilizer use and subsequent Cd enrichment in agricultural soils. However, the optimum mixing ratio of compost and phosphate fertilizer is of paramount importance to obtain the desired outcome. In this study, experimental pot trials were performed to assess plant growth and Cd accumulation in two leafy vegetables, red amaranth (Amaranthus cruentus) and water spinach (Ipomoea aquatica), grown in Cd-contaminated loamy sandy soil under varying rates of compost and phosphate fertilizer application, either alone or in mixture. The study revealed that application of compost in combination with phosphate fertilizer is more effective from both environmental and economic perspectives rather than the application of compost alone, wherein 10 t/ha compost in combination with 40 kg/ha phosphate fertilizer was found as the best treatment for reducing Cd phytoaccumulation in both vegetable species and increasing the plant growth. Moreover, this optimum mixing ratio of compost and phosphate fertilizer showed positive impacts on soil pH and EC. The results also observed that phytoaccumulation of Cd decreases with decreasing the rate of phosphate fertilizer application, either alone or in mixture. Moreover, further study is necessary to determine the impact of combined treatments on microorganisms influencing Cd dynamics in soils.

Compost inputs, cropping system, and rotation phase drive aggregate‐associated carbon

AbstractIn the central Great Plains of North America, winter wheat (Triticum aestivum L.) is often rotated with fallow periods. Tillage and the reduced return of C inputs have led to extensive soil degradation and loss of soil organic matter. Composted beef manure has the potential to restore soil organic matter and soil function. The aim of this study was to determine the effects of compost application rate and grain vs. forage rotations on soil structure and aggregate‐associated C stabilization. The study assessed two dryland rotations of wheat–fallow and triticale (×Triticosecale Wittm. ex A. Camus)/pea (Pisum sativum L.)–fallow, and three compost rates: a control with nothing added (0×), 22.9 t ha–1 (1×), and 108.7 t ha−1 (5×) applied every 2 yr. After 8 yr, total C inputs were positively correlated with total soil organic C, the proportion of macroaggregates in the whole soil, and the mean weight diameter of soil aggregates. The increased C storage in macroaggregates was associated with an increase in the particulate organic matter and microaggregates within macroaggregates. Soils receiving the 5× compost rate had increased mid‐infrared absorbance at the amide II band, in agreement with the decreased soil C/N ratio. Aggregate fractions of the wheat‐based system tended to be more enriched in C than those of the forage‐based rotation. Additionally, soil coming out of fallow tended to have aggregate fractions that were depleted in soil C. Our findings indicate that compost can improve soil structure and aggregate‐associated C stabilization in dryland agroecosystems, whereas cropping system and rotation phase are also important to consider in the long‐term management of SOM.

Soil micromorphological and physical properties after application of composts with polyethylene and biocomponent-derived polymers added during composting

Composts are considered to be one of the best soil amendments. However, the effects of composts with added polymeric materials on soil physical, hydraulic, and micromorphological properties have not been widely discussed. Changes in soil physical properties influence the numerous services that soils provide. We studied the impacts of composts with the addition of three different polymers (F1–F3) produced from polyethylene and thermoplastic corn starch on the physical, hydraulic, and micromorphological properties of two soils, a Cambic Phaeozem and a Luvic Phaeozem. Applying composts with polymers had limited or no significant effect on soil bulk density and porosity, but increased the field water capacity by 18%–82% and 3%–6% and the plant-available water content by 15%–23% and 4%–17% for the Cambic Phaeozem and Luvic Phaeozem, respectively. The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem. It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate. Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.

Short-term Effect of Eucalyptus Wood-based Compost on Biological Fertility of Soils under Avocado Plantations

ABSTRACT This study investigated the effects of a eucalyptus-based compost on soil microbial community and enzyme activities of soils under avocado plantations in Limpopo, South Africa. It was hypothesized that compost application rate and time-post application would determine the abundance of biological organisms and enzyme activities. Experiments were conducted on 8-year-old ‘Hass’ avocado orchards. A repeated measures design with four compost treatments (0, 5, 10, and 15 ton ha−1 year−1), replicated three times was used. Thermophilic compost was prepared from locally sourced Eucalyptus wood chips (40%) and sawdust (20%), chicken manure (20%), and cattle manure (20%) stock feed. Soil samples were collected at three-month intervals for a period of nine months and analyzed for soil biota and enzyme activities. The results showed that compost application led to improved soil microbial counts and the effects were compost application rate and time dependent. The highest microbial counts were realized at 15 tons ha−1 and increased with time post compost application. Phosphatase, β-glucosidase, and urease were slightly increased at 10 and 15 tons ha−1 whereas fluorescein di-acetate was not affected by compost application rates. Compost application rates did not show a consistent effect on soil enzymes activities across sites and time.

Efficacy of Selected Crop Residues and Rock Phosphate in Improving the Quality of Cattle Manure

ABSTRACT Cattle manure (CM) is noted for its poor nutrient quality especially in Ghana where most cattle are fed on a free range. There is therefore a need to improve its quality since it is a vital nutrient resource for smallholder farmers. An experiment was thus carried out by composting cocoa pod husk (CPH), palm kernel cake (PKC) and rock phosphate (RP) to investigate their effectiveness for use as nutrient sources for improving the fertilizer value of cattle manure (CM). Four compost ratios (CM + PKC (3:1), CM + CPH (3:1), CM + RP (3:1) and CM + PKC + CPH + RP (3:1:1:1)) were formulated and replicated three times in Randomized Complete Block Design (RCBD). The findings showed that, addition of CPH, PKC and RP to CM improved the fertilizer value of cattle manure. The CM + PKC + CPH + RP (3:1:1:1) compost increased the nitrogen (N), phosphorus (P) and potassium (K) contents of cattle manure by 73%, 145% and 50%, respectively and was therefore considered the most effective in enhancing the nutrient value of cattle manure. This compost was thus evaluated through field application to maize. The study also revealed that increasing the application rate of compost increased maize grain yields. Hence, cocoa pod husk, palm kernel cake and rock phosphate can be exploited for use as important resources for improving the fertilizer value of cattle manure.

Progress of Soil Fertility and Soil Health Management Research for Arabica Coffee Production in Ethiopia

Soil degradation is one of Ethiopia's most severe concerns, contributing for the country's low coffee production. Researchers have been conducted by different organizations for the past five decades to ameliorate the challenges. The goal of this review was to summarize and document major research achievements recorded so far and recommend future research directions. As a result, mixing coffee pulp and husk in the composting pile with organic elements like farm yard manure and leguminous plants generates nutritionally high-quality compost in 45 days. In terms of increasing coffee yield, decomposed coffee husk (DCH) was found to be superior to <i>Sesbaniasesban</i> compost. Compost application rates of 5 to 10 tons ha^-1 (2 to 4 kg tree^-1 in dry weight base) and an equal proportion of soil incorporation and surface (50:50%) application techniques were found to be superior in increasing coffee yield. 50% recommended NP mineral fertilizer (RMF) (172 and 77 kg ha^-1 NP, respectively) + 50% recommended (DCH (10 ton ha^-1 or 4 kg tree^-1 on a dry weight basis), 50% RMF + 75% DCH, and <i>Desmodium</i>spp (green manure crop) + RMF (172 and 63 kg ha^-1 NP, respectively) significantly (<I>P</I>≤0.05) promote clean coffee yield at Agaro, Haru and Jimma, respectively. Forest soil or blends of top soils, compost and sand in 3:1:0 and 2:1:1 ratio, or organic manure and top soil mixture in 1:4, 2:4 and 3:4 ratios, produced strong and healthy coffee seedlings. A nursery pot amended with 750 mg P pot^-1 (2.5 kg soil) and 2.31 g lime + 250 mg P pot^-1 and 10 g lime + 800 mg P pot^-1 produced released pure line and hybrid seedlings, respectively, with superior dry matter yield at Jimma. Similarly, at Haru, an application of 4 g pot^-1 lime + 12.5 g pot^-1 DCH and 18.75 g pot^-1 DCH was a promising ameliorating management for acid soil for production of vigorous coffee seedlings for field planting. Future research should concentrate on evaluating other organic inputs and combined reclamation of lime-mineral fertilizer-compost, frequency of application, economic benefits, and long-term effects on soil physicochemical properties, coffee yield and bean quality, and establish cost effective soil fertility management in coffee-growing areas of the country. Furthermore, timely revision and calibration of mineral fertilizer recommendations made in the past with newly released coffee genotypes has become critical.

YIELD OF TOMATO CROP IRRIGATED WITH UNTREATED INDUSTRIAL SEWAGE EFFLUENT AND REMEDIATED WITH POTASSIUM SILICATE AND COMPOST APPLICATIONS

An experiment was conducted for the two successive seasons of 2017 and 2018 to investigate the deleterious effect of irrigating tomato plants with untreated industrial waste water and the possible ameliorating effects of compost and potassium silicate applications on the growth and production of the grown plants. Tomato seedlings of hybrid K186 were transplanted at the four-true leaf stage and irrigated with untreated waste effluent. Compost was applied during the soil preparation at rates of 0 (control), 10, 20, and 30 m3 /feddan. Potassium silicate was sprayed on the plants three times; at 20, 40 and 60 days after transplanting in the concentrations of 0 (control), 3, 4 and 5 cm3 /l. Results revealed that vegetative growth and fruit yield of treated plants were increased by increasing compost and potassium silicate rates compared by the control (without compost and potassium silicate).The interaction effect of the treatment showed an added effect of both treatments on all measured parameters. Plant length, number of leaves and number of branches increased as the application rate of compost and potassium silicate increased. Similarly, SPAD readings showed similar positive and significant trend. In the contrary, contents of Zn, Pb, Ni, Cd and Mnresponded negatively and significantly to the interaction effect of the treatments showing the highest effect with the treatment 5 cm3 potassium silicate associated with 30 m3 compost application compared to the control. Similar to the positive effect on vegetative growth, the positive additive effect of both treatments was clear on total fruit yield where the highest effect was recorded with the treatment combining the highest rate of application of both potassium silicate and compost. It could be concluded that potassium silicate and compost applications can ameliorate the harmful effects of heavy metals in the soil.

EFFECTS OF COMPOST ON SOIL PROPERTIES AND YIELD OF PINEAPPLE (Ananas comusus L. MERR.) ON RED ACID SOIL, LAMPUNG, INDONESIA

Compost is an organic matter commonly used to improve the chemical and physical properties of soil, especially of marginal soil, where the limiting factors of the soil fertility are the lack of organic matter and low soil pH. One aim of this study is to determine the effect of compost application on the improvement of the chemical and physical properties of acid soils planted with pineapple. Another aim of this study is to determine the effect of compost in reducing the foliar fertilizer and the influence of this reduction on the pineapple yield. A factorial experiment was arranged in a randomized block design with two factors and three replications. The first factor was the rate of compost application with the following treatments: K0: no compost, K25: compost 25 t ha-1 and K50: compost 50 t ha-1, while the second factor was the reduction of foliar chemical fertilizer with the following treatments: P100: 100% of the standard fertilizer, P80: 80% of the standard fertilizer and P60: 60% of the standard fertilizer. The total combined treatments, i.e., nine treatments, consisted of K0P100, K0P80, K0P60, K25P100, K25P80, K25P60, K50P100, K50P80 and K50P60 with three replications. The results showed that the compost could improve the chemical and physical properties of acid soils, and the application of the compost dose of 25 t ha-1 enabled a reduction of foliar chemical fertilizer by 40% with no loss in yield. Keywords: Compost, Foliar spray, Pineapple, Reduction of foliar fertilizers, Red soil

Feasibility of urban waste for constructing Technosols for plant growth

An alternative for sustainable urban development is to revegetate cities with the construction of planters as well as to recover degraded sites. The objective of this work was to characterize urban waste materials produced in Mexico City and to evaluate their potential for constructing Technosols for plant growth, as an alternative to use in revegetating the city without affecting natural landscapes. Construction and demolition waste materials amended with different application rates of compost made out of gardening wastes from Mexico City green areas were tested. Nine mixtures were prepared; three based on concrete, three based on demolition waste and three based on excavation waste. Changes on physical, chemical and physicochemical properties of these mixtures, namely nutrient contents, water retention and aeration capacity, were monitored in a twelve-month experiment. The mineralogy and the risk regarding the release of heavy metals and trace elements were also evaluated in the soluble fraction. The constructed Technosols were appropriate, to a greater or lesser extent, for tomato plant growth. Soil pH and soil electrical conductivity (EC) were the main factors defining their suitability; both parameters changed over time due to the washing of salts. The particle size of the mineral materials as well as the application rates of compost used in the construction of the Technosols resulted in adequate water holding capacity and soil aeration for plant growth. The type of parental materials defined the majority of the Technosol characteristics as well as their ability to function as a plant support. The concentrations of readily available heavy and trace metals were not a limitation for plant growth. However, potential co-transport of these elements with soluble organic matter should be considered in further research.

Plastic in compost: Prevalence and potential input into agricultural and horticultural soils

To maintain and improve soil fertility, compost application is a widely recommended practice. We hypothesized that this practice is, however, also a main entry path for plastic into soil. Hence, we i) quantified the prevalence of plastic in eight composts from different composting plants and hardware stores to derive estimations about related plastic inputs into soil, and ii) characterized the properties of these plastic residues in regard to size and shape for further risk assessment. Plastic remains were analyzed via density separation (ZnCl2) and light microscopy. Testing this method recovered 80 ± 29% of spiked plastic items. Applying this method revealed that all composts contained plastic particles in detectable amounts, with contents ranging from 12 ± 8 to 46 ± 8 particles kg−1, corresponding to calculated plastic weights of 0.05 ± 0.08 to 1.36 ± 0.59 g kg−1. Because of this high variability, an a-priori discrimination of plastic loads between compost types cannot be achieved. Upscaling these loads to common recommendations in composting practice, which range from 7 to 35 t compost ha−1, suggest that compost application to agricultural fields goes along with plastic loads of 84,000 to 1,610,000 plastic items ha−1 per year (a), respectively, amounting to 0.34 to 47.53 kg plastic ha−1 a−1. Large potential inputs should thus also occur for horticultural soils, where application rates of compost usually vary between 6.48 and 19.44 t ha−1, therewith resulting in a minimum plastic contamination of 77,770 plastic items and 0.31 kg plastic ha−1 a−1, but a maximum amount of up to 894,240 plastic items and 26.4 kg plastic ha−1 a−1. We conclude that compost application must be considered as potential source of plastic for both agricultural and horticultural soils, and technical solutions are needed to minimize these contamination risks while continuing this practice as important option to secure soil health.

Effects of Fruit and Vegetable Wastes and Biodegradable Municipal Wastes Co-Mixed Composts on Nitrogen Dynamics in an Oxisol

Organic waste generation in developing countries is increasing and appropriate disposal methods are needed. An open aerobic composting using 20 L bins was carried out using 6 composts made using ratios of 3:1, 1:2 and 1:4 fruit and vegetable wastes (FVW):biodegradable municipal waste (BMW), with and without addition of homemade indigenous microorganisms (IMO), for 30 days to monitor compost quality. The nitrogen contents of the composts ranged from 1.52 to 2.76% N equivalent to 76–138 kg N ha−1 at 5 t ha−1 compost application rates. Heavy metals measured were below permissible levels of compost quality standards. Selected composts were incubated for 60 days to study nitrogen mineralization dynamics when applied to an Oxisol at the rates of 0, 5 and 10 t ha−1. The results showed significant differences (p ≤ 0.05) in the amounts of NH4-N, NO3-N and cumulative NH4-N + NO3-N released. Ammonium nitrogen released was higher on days 3, 21 and/or 40 for composts 3:1 − IMO at 10 t ha−1, 3:1 + IMO at 10 t ha−1 and 3:1 − IMO at 5 t ha−1. Cumulative N (NH4 -N + NO3 -N) released over control were 77.98, 64.09 and 64.35% higher for application of 3:1 + IMO, 1:2 − IMO and 1:2 + IMO, respectively, at an application rate of 10 t ha−1. The increased nitrogen content, low heavy metals concentrations and the amount of mineralized N from the composts exhibit potential for increased nutrient availability when applied to a soil.

Compost Application to Degraded Vineyard Soils: Effect on Soil Chemistry, Fertility, and Vine Performance

A two-year experiment investigated the effects of compost application rate on soil chemical properties, vine nutrient status, vine performance, and grape juice characteristics in a degraded vineyard soil in northern California. The intent of the research was to identify vineyard management strategies to improve soil fertility and to identify optimal compost application rates. We applied composted steer manure at three rates (11.2, 22.4, and 33.6 t/ha) in a randomized complete block design before the 2012 growing season. Pruning and berry weight increased over the control at the highest application rate in both years, while vine yield significantly increased over the control in year two. Polynomial orthogonal contrasts suggest that pruning weight, vine yield, and berry weight increased linearly with increasing compost application rate in 2012, and that vine yield and berry weight increased linearly and quadratically with compost application rate in 2013. Measured soil properties increased from compost application, including nitrogen (N), carbon, pH, exchangeable potassium (K), manganese, and calcium and available phosphorus (P, Olsen-P), while phosphorus fixation decreased. Vine petiole nutrients (N, P, and K) significantly increased from compost application in both years. Juice characteristics (pH, total soluble solids, and titratable acidity) were unaffected by compost application. Similarly, vine balance was unaffected by compost application. All vine metrics improved at the highest application rate, and soil chemical properties increased with the two highest application rates. Therefore, significant benefits to soil fertility and vine performance can be achieved for at least two years in degraded vineyard soils following a single dose of compost at higher application rates (22.4 and 33.6 t/ha) without compromising juice characteristics or vine balance.

Assessment of Fertilizer Usage by Food Crops at the National Level

Korea is one of countries that have high application rates of inorganic fertilizers. Recently, environmental pollution has been announced due to overuse of fertilizer. To reduce the fertilizer usage, agricultural policies in terms of environmental sustainability has been introduced since the 1990s. This study aims to investigate total fertilization rates by nutrients and food crops in 9 provinces of Korea. In results, the average of total fertilizer inputs (N-P2O5-K2O) was 18.3-11.2-12.7 kg 10a-1. Total fertilizer usage of potato was 35.5 kg 10a-1 as N that was higher than other crops. The order of contribution to total fertilizer use was inorganic fertilizer > compost > organic fertilizer. As a result, main concern of excess and use of fertilizers were focused on inorganic fertilizer. However, because of the high nutrient content of compost, the application rate of compost should be monitored and controlled. Therefore, long-term monitoring and proper training is required to understand nutrient characteristics of fertilizer and to reserve environmental sustainability in agriculture. Distribution of nutrient in food crops with different fertilization.

Dynamics of ammonia oxidizers and denitrifiers in response to compost addition in black soil, Northeast China.

Organic fertilizer application could have an impact on the nitrogen cycle mediated by microorganisms in arable soils. However, the dynamics of soil ammonia oxidizers and denitrifiers in response to compost addition are less understood. In this study, we examined the effect of four compost application rates (0, 11.25, 22.5 and 45 t/ha) on soil ammonia oxidizers and denitrifiers at soybean seedling, flowering and mature stage in a field experiment in Northeast China. As revealed by quantitative PCR, compost addition significantly enhanced the abundance of ammonia oxidizing bacteria (AOB) at seedling stage, while the abundance of ammonia oxidizing archaea was unaffected across the growing season. The abundance of genes involved in denitrification (nirS, nirK and nosZ) were generally increased along with compost rate at seedling and flowering stages, but not in mature stage. The non-metric multidimensional scaling analysis revealed that moderate and high level of compost addition consistently induced shift in AOB and nirS containing denitrifers community composition across the growing season. Among AOB lineages, Nitrosospira cluster 3a gradually decreased along with the compost rate across the growing season, while Nitrosomonas exhibited an opposite trend. Network analysis indicated that the complexity of AOB and nirS containing denitrifiers network gradually increased along with the compost rate. Our findings highlighted the positive effect of compost addition on the abundance of ammonia oxidizers and denitrifiers and emphasized that compost addition play crucial roles in shaping their community compositions and co-occurrence networks in black soil of Northeast China.

Quantifying nutrient recovery efficiency and loss from compost-based urban agriculture.

The use of compost in urban agriculture offers an opportunity to increase nutrient recycling in urban ecosystems, but recent studies have shown that compost application often results in phosphorus (P) being applied far in excess of crop nutrient demand, creating the potential for P loss through leachate and runoff. Management goals such as maximizing crop yields or maximizing the mass of nutrients recycled from compost may inadvertently result in P loss, creating a potential ecosystem disservice. Here, we report the results from the first two years of an experimental study in which four different crops grown in raised-bed garden plots with high background P and organic matter received one of two types of compost (municipal compost made from urban organics waste, or manure-based compost) at two different levels (applied based on crop N or P demand), while additional treatments received synthetic N and P fertilizer or no soil amendments. Because of the low N:P ratio of compost relative to crop nutrient uptake, compost application based on crop N demand resulted in overapplication of P. Crop yield did not differ among treatments receiving compost inputs, and the mass of P recovered in crops relative to P inputs decreased for treatments with higher compost application rates. Treatments receiving compost targeted to crop N demand had P leachate rates approximately twice as high as other treatments. These results highlight tradeoffs inherent in recycling nutrients through UA, but they also show that targeted compost application rates have the capacity to maintain crop yields while minimizing nutrient loss. UA has the potential to help close the urban nutrient loop, but if UA is to be scaled up in order to maximize potential social, economic, and environmental benefits, it is especially important to carefully manage nutrients to avoid ecosystem disservices from nutrient pollution.

Quantifying the Farmland Application of Compost to Help Meet California's Organic Waste Diversion Law.

California's landmark waste diversion law, SB 1383, mandates the diversion of 75% of organic waste entering landfills by 2025. Much of this organic waste will likely be composted and applied to farms. However, compost is expensive and energy intensive to transport, which limits the distance that compost can be shipped. Though the diversion of organic waste from landfills in California has the potential to significantly reduce methane emissions, it is unclear if enough farmland exists in close proximity to each city for the distribution of compost. To address this knowledge gap, we develop the Compost Allocation Network (CAN), a geospatial model that simulates the production and transport of waste for all California cities and farms across a range of scenarios for per capita waste production, compost application rate, and composting conversion rate. We applied this model to answer two questions: how much farmland can be applied with municipal compost and what percentage of the diverted organic waste can be used to supplement local farmland. The results suggest that a composting system that recycles nutrients between cities and local farms has the potential to play a major role in helping California meet SB 1383 while reducing state emissions by -6.3 ± 10.1 MMT CO2e annually.