Temperature and Chemical Changes During Composting of Broiler Litter

Composting broiler litter (a mixture of manure, bedding material, and wasted feed) with commonly available high-C substrates may be a viable alternative to reduce current land disposal practices for litter. Broiler litter with wood shavings as a bedding material and broiler litter with peanut hulls as a bedding material were composted with wheat straw, peanut hulls, pine bark and paper mill sludge in 0.33 m³ batch reactors. Litters and C substrates were mixed to achieve C:N ratios of approximately 30:1. Dry weight, total N, total C, temperature, electrical conductivity and pH were determined at regular intervals. Maximum temperatures peaked near 70°C within 2.25 d after mixing peanut hulls with litter and within 2.58 d for pine bark and litter. Composts made from paper mill sludge approached 50°C within 3.71 d. Wheat straw composts never exceeded 40°C which could present potential health problems associated with pathogenic microorganisms. Mass loss and C:N ratio gradually declined and stabilized approximately 84 d after mixing. Mass loss averaged 73 percent for wheat straw compost, 33 percent for peanut hull composts, and 16 percent for the other mixes. Wheat straw compost C:N ratios stabilized near 14:1 and other mixes remained above 20:1, indicating N limited conditions for complete composting. Compost pH was 5.8 after 84 d from pine bark composted with wood shaving litter and was significantly lower than pH from paper mill sludge compost with an average pH of 6.9 but similar to all other compost mixes (pH 6.7). Electrical conductivity ranged from 0.35 S m^?1 for paper mill sludge composted with wood shaving litter to 0.91 S m^?1 from wheat straw composted with peanut hull litter. Composting temperature varied considerably among C sources and all required at least 72 d of curing to stabilize the C:N ratio. Composts made from wheat straw were most effective for waste reduction but temperatures were below the 50°C level generally considered necessary to kill pathogens.     

Increased total nitrogen content of poultry manure by decreasing water content through composting processes

Microbial mineralization of urea and uric acid in poultry litter can lead to loss of nitrogen (N) content and its value as a fertilizer. To minimize the loss of N in the composting processes, controlling the water content in litters is a key to reduce the mineralization processes of N compounds. The N content of litter may be influenced by diets, hen age and the type of poultry houses used. The objectives of the present study were i) to determine the relationship between the water content and the decomposition rate of uric acid in poultry litter and ii) to investigate the effect of hen age and crude protein (CP) percentages in diets on the N content of poultry litter. A layer feeding trial was conducted in two poultry farms with windowless and open-floor houses. An incubation study of poultry litter was performed under different levels of water content. Our study found that the diet CP percentage (16.5–18%) and the growth stage of laying hens did not have a significant effect on the amount of total N (52–56?g?kg^?1) and uric acid-N (26–31g?kg^?1) in fresh litters. At the 7^th day of litter incubation study, the concentration of uric acid-N was 22 g kg^?1 in litters with a water content of 35%, whereas it further decreased to less than 1.3 g kg^?1 in litters with a water content of 55% and higher levels. The decomposition rate of uric acid-N in litter was 0.3–3.1g?kg^?1?day^?1 in the windowless house and 3.1–7.1g?kg^?1?day^?1 in the open-floor house. Decomposition of uric acid in litters was positively correlated to the litter moisture content that is controlled to be lower in windowless houses (40–50%) than in open-floor houses (55–80%) during the composting period. Our study suggests that the use of windowless houses for layer chicken production is effective for producing poultry manure with a high N content.     

Tillage and amendment effects on soil carbon and nitrogen mineralization and phosphorus release

The influence of tillage and nutrient amendment management on nutrient cycling processes in soil have substantial implications for environmentally sound practices regarding their use. The effects of 2 years of tillage and soil amendment regimes on the concentrations of soil organic matter variables (carbon (C), nitrogen (N) and phosphorus (P)) and C and N mineralization and P release were determined for a Dothan fine-sandy loam soil in southeastern Alabama. Tillage systems investigated were strip (or conservation) and conventional tillage with various soil nutrient amendments that included no amendment, mineral fertilizer, and poultry waste (broiler litter). Surface soil (0–10 cm depth increment) organic matter variables were determined for all tillage/amendment combinations. Carbon and N mineralization and P release were determined on surface soils for each field treatment combination in a long-term laboratory incubation. Soil organic P concentration was 60% greater in soils that had been conventionally tilled, as compared with strip-tilled, both prior to and following laboratory incubation. Carbon and N mineralization results reflected the effects of prior tillage amendment regime, where soils maintained under strip-till/broiler litter mineralized the greatest amount of C and N. Determination of relative N mineralization indicated that strip tillage had promoted a more readily mineralizable pool of N (6.1%) than with conventional till (4.2%); broiler litter amendments had a larger labile N fraction (6.7%) than was found in soils receiving either mineral fertilizer (4.1%) or no amendment (4.7%). Tillage also affected P release measured during the incubation study, where approximately 20% more inorganic P was released from strip-tilled soils than from those maintained under conventional tillage. Greater P release was observed for amended soils as compared with soils where no amendment was applied. Results from this study indicate that relatively short-term tillage and amendment management can significantly impact C, N, and P transformations and transfers within soil organic matter of a southeastern US soil.     

Influence of organic by-products and nitrogen source on chemical and microbiological status of an agricultural soil

We assessed the influence of the addition of four municipal or agricultural by-products (cotton gin waste, ground newsprint, woodchips, or yard trimmings), combined with two sources of nitrogen (N), [ammonium nitrate (NH₄NO₃) or poultry litter] as carbon (C) sources on active bacterial, active fungal and total microbial biomass, cellulose decomposition, potential net mineralization of soil C and N and soil nutrient status in agricultural soils. Cotton gin waste as a C source promoted the highest potential net N mineralization and N turnover. Municipal or agricultural by-products as C sources had no affect on active bacterial, active fungal or total microbial biomass, C turnover, or the ratio of net C:N mineralized. Organic by-products and N additions to soil did not consistently affect C turnover rates, active bacterial, active fungal or total microbial biomass. After 3, 6 or 9 weeks of laboratory incubation, soil amended with organic by-products plus poultry litter resulted in higher cellulose degradation rates than soil amended with organic by-products plus NH₄NO₃. Cellulose degradation was highest when soil was amended with newsprint plus poultry litter. When soil was amended with organic by-products plus NH₄NO₃, cellulose degradation did not differ from soil amended with only poultry litter or unamended soil. Soil amended with organic by-products had higher concentrations of soil C than soil amended with only poultry litter or unamended soil. Soil amended with organic by-products plus N as poultry litter generally, but not always, had higher extractable P, K, Ca, and Mg concentrations than soil amended with poultry litter or unamende soil. Agricultural soil amended with organic by-products and N had higher extractable N, P, K, Ca and Mg than unamended soil. Since cotton gin waste plus poultry litter resulted in higher cellulose degradation and net N mineralization, its use may result in faster increase in soil nutrient status than the other organic by-products and N sources that were tested. Received: 15 May 1996     

Potentially mineralizable nitrogen from organic materials applied to a sandy soil: fitting the one-pool exponential model

Abstract. Over the last three decades there has been a great increase in the production of waste from urban, industrial and agricultural activity that could be recycled as a source of plant nutrients, and used to enhance soil quality. The use of these materials could partially offset the need for mineral fertilizers, giving both economic and environmental benefits. An incubation experiment was carried out using different organic waste materials applied to a Cambic Arenosol. Air-dried soil was mixed with increasing amounts of composted solid municipal waste, secondary pulp-mill sludge, hornmeal, poultry manure, solid phase from pig slurry, and composted pig manure, resulting in applications equivalent to 0, 40, 80, 120, 160 and 200 kg ha⁻¹ of Kjeldahl nitrogen. The samples were incubated for 244 days under a controlled environment of 24 °C and 60% water holding capacity of the soil. The increasing amounts of waste applied always led to a greater amount of potentially available nitrogen present in the soil/waste mixture. Based on the proportion of their active N fraction, wastes were ranked: poultry manure>hornmeal>solid phase from pig slurry>composted pig manure>secondary pulp-mill sludge>composted municipal solid waste. The results were well described by a one-pool exponential mineralization model, and mineral N formation was proportional to the quantity of waste applied. Of the wastes tested, those from animal sources showed greater nitrogen mineralisation. Nitrification was rapid, and concentrations of ammonium nitrogen remained relatively small.     

Comparative evaluation of broiler and layer poultry manure for greenhouse lettuce production

Abstract

Disposing poultry manure from broiler and layer flocks by its incorporation into the soil was evaluated on greenhouse lettuce (Lactuca sativa L. cv. Paris Island cos). Floor litter that contains the manure mixed with sawdust and wood shaving, was 8 weeks old from broilers and one year old from layers. Broiler manure had 19% moisture and 5.5% N, while layer manure had 22% moisture and 3.7% N. Application of 27.5 ton/ha broiler manure and 18 ton/ha layer manure, on wet basis, gave comparable yield of lettuce as did an application of 100 kg N/ha from NH₄NO₃ in 2 split applications, and an unfertilized treatment. The manure was effective for lettuce growth 10 months after its incorporation in the soil. The highest yield was in manure treated plots, however, the lack of significant response in yield is due to the sufficient levels of soil NO₃‐N and available P. There was no effect on soil EC, pH, and available P due to the treatments; however, soil NO3‐N was significantly increased under all fertilized treatments. Leaf concentration of PO4‐P was not affected by the treatments, but NO3‐N was significantly increased under all fertilized treatments. It may be concluded that broiler and layer poultry manure when disposed of by soil incorporation, are equally effective as a fertilizer for a leafy crop such as lettuce.     

Litter quality effects on soil carbon and nitrogen dynamics in temperate alley cropping systems

Microcosm and litterbag experiments were conducted to determine the effects of litter quality, soil properties and microclimate differences on soil carbon (C) and nitrogen (N) mineralization in alley cropping systems. Bulk soils were collected from 0 to 20 cm depth at three sites: a 21-year old pecan (Carya illinoinensis)/bluegrass (Poa trivialis) intercrop (Pecan site) in north-central Missouri, a 12-year old silver maple (Acer saccharinum)/soybean (Glycine max)–maize (Zea mays) rotation (Maple site) in northeastern Missouri and a restored prairie site (MDC site) in southwestern Missouri. Seven tree and crop litters with varying composition were collected, including pecan, silver maple, chestnut and walnut leaf litter (tree litter) and maize, soybean and bluegrass residues (crop litter). Aerobic microcosm incubations were maintained at 25 °C and a soil water potential of −47 kPa. Unamended MDC soil mineralized 24 and 18% more CO₂ than the Pecan and Maple soils, respectively. Soil amended with crop litter mineralized on average 32% more CO₂ than when amended with tree litter. Net N mineralization from soybean litter was 40 mg kg⁻¹, while all other litter immobilized N for various durations. A double pool and a single pool model best described C and N mineralization from amended soils, respectively. Cumulative CO₂ mineralized, labile C fraction (C₁) and potentially mineralizable C (C₀) were correlated to litter total N and lignin contents and to (lignin + polyphenol):N ratio. In the field, bluegrass litter decomposed and released N twice as fast as pecan leaf litter. Soybean, maize and silver maple litter released 84, 75 and 63% of initial N, respectively, 308 days after field placement, while no differences in mass loss was observed among the three litter materials. At the Maple site, mass and N remaining, 308 days after field placement was lower at the middle of the alley, corresponding to higher soil temperature and water content. No differences in mass loss and N release patterns were observed at the Pecan site. Microclimate and litter quality effects can lead to differences in nutrient availability in alley cropping systems.     

Effects of Linear Alkylbenzene Sulphonates (LASs) on Exogenous Organic Matter Content and Evolution in Sewage Sludge–Amended Soils

Abstract

Linear alkylbenzene sulphonates (LASs) are anionic surfactants commonly used in commercial detergents. A potential risk associated with the recycling of sewage waste materials is the presence of LASs and their primary degradation products, which could accumulate in sludge, especially during anaerobic processing. The long‐term accumulation of these contaminants in soils and especially the potential disturbance of soil functions need to be studied in more detail. In our study, the influence of the amendment added to an agricultural soil with different organic wastes containing LASs on organic matter content and nitrogen (N) content evolution and mineralization was studied in field conditions. A completely randomized 3×3 factorial arrangement, representing two sewage sludge types (composted and uncomposted) and three levels of LAS presence (0, 15, and 30 g/m²) in treated soils, was established using field plots (7×2 m); the results are compared with untreated plots. Statistical models based on covariance analysis were used to understand the dynamics of and the main factors influencing carbon (C) and N mineralization in sewage sludge amended–soils in the presence of LAS. LAS seemed to alter nitrogen mineralization, especially the nitrate dynamics.     

Impact of drying method on broiler litter analyses

Abstract

Drying broiler litter prior to chemical analyses may alter its chemical composition and result in excessive or inadequate nutrient applications to crops if such analyses are used for recommendation purposes. A study was conducted to determine the effect of drying method and temperature on broiler litter N, P, K, Cu, Fe, and Zn contents. Treatments consisted of no drying (ND), air drying (AD), oven drying at 40°C (OD40), oven drying at 60°C (OD60), microwave drying at 40°C (MW40), microwave drying at 60°C (MW60), and freeze drying at ‐40°C (FD). All drying treatments lost N when compared to ND, and greatest losses were observed with the FD, OD60 and AD treatments; losses were 15, 12 and 12% of the ND total N, respectively. Changes in broiler litter P, K, Cu, Fe and Zn due to drying were small and were inconsequential with respect to agronomic and environmental considerations. It appeared that maintaining broiler litter in a moist, refrigerated state before chemical analyses was more desirable than drying. However, our results show that from a practical standpoint, the MW40 treatment may be a desirable alternative.     

Mineralization of Nitrogen in Soils Amended with Dairy Manure as Affected by Wetting/Drying Cycles

Abstract

Interest in manure management and its effects on nitrogen (N) mineralization has increased in recent years. The focus of this research was to investigate the N‐mineralization rates of different soil types in Coastal Plain soils and compare them to a soil from Illinois. Soils with and without dairy composted manure addition were subjected to different wetting/drying cycles [constant moisture at 60% water‐filled pore space (WFPS) and cycling moisture from 60 to 30% WFPS] under laboratory conditions at three different temperatures (11°C, 18°C, and 25°C). Samples were collected from three different soil types: Catlin (Mollisols), Bama (Ultisols), and Goldsboro (Utilsols). Soil chemical and physical properties were determined to help assess variations in N-mineralization rates. Addition of composted manure greatly impacted the amount of N mineralized. The amount of manure‐derived organic N mineralized to inorganic forms was mainly attributed to the soil series, with the Catlin (silt loam) producing the most inorganic N followed by the Goldsboro (loam) and then Bama (sandy loam). This was probably due to soil texture and the native climatic conditions of the soil. No significant differences were observed between the constant and cycling moisture regimens, suggesting that the imposed drying cycle may not have been sufficient to desiccate microbial cells and cause a flush in N mineralization upon rewetting. Nitrogen mineralization responded greatly to the influence of temperature, with the greatest N mineralization occurring at 25°C. The information acquired from this study may aid in predicting the impact of manure application to help increase N‐use efficiency when applied under different conditions (e.g., climate season) and soil types.     

Effect of lignite amendment on carbon and nitrogen mineralization from raw and composted manure during incubation with soil

The application of animal manure as a source of plant nutrients requires the determination of the amount and pattern of nutrient mineralization from manure.A laboratory incubation study was conducted to investigate the influence of lignite amendment and lignite type on carbon(C) and nitrogen(N)mineralization in raw(feedstock) and composted cattle manure following application to soil at 30 and 60 t ha^-1.The mineralization of C and N was determined by measuring changes in CO2 evolution ...     

Direct and residual effects of pulp and paper mill sludge on crop yield and soil mineral N

Abstract. Paper sludge composted or stored in static piles for six months was compared to raw and lime-stabilized sludge in a three-year pot experiment (loam) and a four-year field experiment (silt loam) at rates of up to 40 t DM ha^-l. The original sludge contained equal amounts of fibre sludge and biological sludge, mixed with bark in 1:1 ratio to improve the structure. The N content in composted sludge (1.30%) was markedly lower than that of the uncomposted piles (1.98%), indicating significant loss during composting. The yield results were generally inversely proportionate to the C:N ratios of the sludges applied. Sludge from the uncomposted piles gave significant grain yield increases in the year following sludge application, while the other sludge types gave variable results. In the residual years there was, generally, a small but positive effect on yield from all the sludge types. The N and P content in grain generally increased with sludge application, but only the higher rates gave statistically significant increases. Sludge application also increased the Zn content in grain, while Mn, B and Cu was less affected. The increase in Cd content was very small. The 40 t ha^-l sludge rate tended to increase the residual mineral N in soil at the field site and thus the risk of nitrate leaching.     

Mineralization and N Fertilizer Equivalent Value of Composts as Assessed by Tall Fescue (Festuca arundinacea)

The capability to determine nitrogen availability of composts is necessary to ensure that such materials will provide sufficient fertilization to the growing crop and cause minimal environmental degradation. A greenhouse study using tall fescue as a bioindicator was used to evaluate nitrogen availability of two biosolids composts, two mixed yard waste-poultry manure composts, and one commercially-processed poultry litter. Five inorganic nitrogen (as NH₄NO₃-N) treatments applied at 0, 22.5, 45, 67.7, and 90 mg N/kg soil were employed to establish an N calibration curve. Yield, fescue biomass total nitrogen (as total Kjeldahl N (TKN)), and soil TKN and KCl extractable NO₃^?-N and NH₄⁺-N concentrations of the organically amended treatments were compared to the inorganically fertilized treatments to determine amendment N mineralization rates and N fertilizer equivalent values (NFEV). Nitrogen mineralization rates were greatest in the poultry litter (21%) and Panorama yard waste compost (5%) amended pots. The NFEV of these amendments were 49% and 10%, respectively. Wolf Creek biosolids compost and Huck's Hen Blend yard waste compost immobilized N (?5% and 0.18%, respectively), and had percent NFEV of ?0.66% and 0.19%, respectively. Rivanna biosolids compost immobilized N (?15%), but the NFEV was 30% due to the relatively high inorganic N content in the amendment. Nitrogen mineralization and NFEV were generally greater in amendments with greater total N concentrations and lower C:N values. The total N concentration and C:N values were less reliable variables in predicting N mineralization and percent NFEV when a significant portion of the total N was in the inorganic form. Nitrogen equivalency value and N mineralization for each amendment increased with time of sampling, indicating the potential for early season N insufficiency to plants fertilized with compost due to lack of synchrony between N mineralization and plant N needs.     

ESTIMATING SHORT- AND MEDIUM-TERM AVAILABILITY TO CEREALS OF NITROGEN FROM ORGANIC RESIDUES

Overused soil resources and the build-up of organic residues from industrial processes have resulted in increased risk of environmental contamination. Recycling of organic residues from industry by incorporation into agricultural soil, can provide valuable organic amendment as well as supply nutrients to crops. The effect of applying organic amendments to an agricultural sandy soil on the nitrogen nutrition of wheat (Triticum aestivum L.) and residual effects on the growth of a following maize crop (Zea mays, L.), were assessed under semi-controlled environmental conditions and were compared to nitrogen mineralization prediction obtained from an aerobic incubation. Six different organic residues (composted municipal solid waste, secondary pulp-mill sludge, hornmeal, poultry manure, the solid phase from pig slurry and composted pig manure) were added to a Cambic arenosol, incubated or used in pot experiments, to evaluate and try to predict the availability to crop plants of nitrogen released from these materials. Poultry manure was the most effective amendment in making nitrogen available and enhancing nitrogen uptake by wheat plants resulting in greater dry matter yield. The dried solid phase from pig slurry and hornmeal were also beneficial to wheat growth. There was a greater recovery of nitrogen (N), from organic materials studied, by a maize crop. Poultry manure was the residue that provided a greater residual effect on N supply to maize.     

Comparison of humic acids derived from city refuse with more developed humic acids

Abstract

The humic acids (HA) from composted and uncomposted city refuse (CR) were characterized by degradative (oxidation with persulphate and permanganate) and non-degradative techniques (FT-IR and ¹³C-NMR) in order to analyze the effect of the composting process on these HA. They were also compared with commercial HA extracted from leonardite. The carboxyl and carbonyl group content of the HA from CR increased slightly during composting. Since the HA from the composted CR showed a lower N and H content, the FT-IR spectra showed a lower intensity in the bands corresponding to peptides and carbohydrates. Differences were revealed when the HA from both CR were compared with those from leonardite which showed a much lower N and H content and a less aliphatic character. The percentage of degraded products by persulphate was higher for the HA from uncomposted CR. For the HA from both CR the major components among the oxidation products were dicarboxylic acids and normal fatty acids. In the leonardite HA, the major components consisted of benzene polycarboxylic acids. ¹³C-NMR revealed an attenuation of the aliphatic character of the HA from CR with composting.     

Changes in Chemical,Physical and Biological Properties Of Passively-Aerated Cocomposted Poultry Litter And Municipal Solid Waste Compost

Cocomposting of poultry litter with municipal solid waste compost (MSW) was evaluated as a means to stabilize nitrogen and phosphorus in poultry litter and to produce a stable organic soil amendment. Four passively aerated compost piles were established by mixing fixed weight ratios of MSW and composted poultry litter (21:1, 6:1, 3:1, 1:1); moisture was adjusted to 50 percent by weight at pile establishment. These ratios represented a range of initial C:N (26-12) and C:P (150-50) ratios. Composting process parameters monitored over eight months included temperature, oxygen and moisture contents, pH, electrical conductivity, C:N:P ratios, microbial respiration and diversity. Initial feedstock ratios had no significant effect on temperature in the thermophilic phase of composting. After one year of composting, microbial respiration in 21:1 and 6:1 mixtures was high relative to 3:1 and 1:1 mixtures suggesting slow maturation in piles with high MSW content. Salmonella sp. and coliform organisms were detectable for up to 47 days. Results suggest that MSW has potential as a carbon feedstock for poultry litter composting when used in moderate amounts.     

Soil compaction and poultry litter effects on factors affecting nitrogen availability in a claypan soil

Soil compaction may affect N mineralization and the subsequent fate of N in agroecosystems. Laboratory incubation and field experiments were conducted to determine the effects of surface soil compaction on soil N mineralization in a claypan soil amended with poultry litter (i.e., Turkey excrement mixed with pine shavings as bedding). In a laboratory study, soil from the surface horizon of a Mexico silt loam soil was compacted to four bulk density levels (1.2, 1.4, 1.6 and 1.8 Mg m⁻³) with and without poultry litter and incubated at 25 °C for 42 days. A field trial planted to corn (Zea mays L.) was also conducted in 2002 on a Mexico silt loam claypan soil in North Central Missouri. Soil was amended with litter (0 and 19 Mg ha⁻¹) and left uncompacted or uniformly compacted. Soil compaction decreased soil inorganic N by a maximum of 1.8 times in the laboratory study; this effect was also observed at all depths of the field trial. Compacted soil with a litter amendment accumulated NH₄⁺-N up to 7.2 times higher than the noncompacted, litter-amended soil until Day 28 of the laboratory incubation and in the beginning of the growing season of the field study. Ammonium accumulation may have been due to decreased soil aeration under compacted conditions. Application of litter increased soil N mineralization throughout the growing season. In the laboratory study, soil inorganic N in unamended soil was negatively correlated with soil bulk density and the proportion of soil micropores, but was positively related with soil total porosity and the proportion of soil macropores. These results indicate that soil compaction, litter application and climate are interrelated in their influences on soil N mineralization in agroecosystems.     

Broiler Litter as a Sole Nutrient Source for Cotton: Nitrogen,Phosphorus, Potassium,Calcium, and Magnesium Concentrations in Plant Parts

Abstract

The ability of poultry litter to support plant growth by supplying essential plant nutrients in the absence of other sources of the nutrients has not been studied thoroughly. The objectives of this research were to (1) determine the ability of poultry litter, as the sole nutrient source, to provide macronutrients and support growth of cotton (Gossypium hirsutum L.) (2) evaluate the distribution of these nutrients within the different plant parts, and (3) estimate the efficiency with which these nutrients are extracted by cotton. The research was conducted in plastic containers filled with a 2:1 (v/v) sand:vermiculite growing mix under greenhouse conditions. The treatments included broiler litter rates of 0, 30, 60, 90, or 120 g pot^?1 with or without supplemental Hoagland's nutrient solution. Broiler litter supplied adequate amounts of the macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) and supported normal growth of cotton. Tissue nutrient analysis showed that the concentration of N, P, K, and Mg in the upper mainstem leaves was within published sufficiency ranges for cotton growth. Evaluation of the N distribution indicated that the cotton plant partitions N to reproductive parts when faced with deficiency of this nutrient and favors allocating N to new leaf growth once the requirement for reproductive growth is met. The partitioning of P was similar to that of N but less distinct. Cotton extracted Mg and K with greater efficiency (up to 58%) than the other nutrients and stored these nutrients in older leaves. The extraction efficiency of N ranged between 21% at 120 g pot^?1 litter and 27% at 30 g pot^?1 litter. Phosphorus was the most poorly extracted nutrient, with only 16% of the total applied P extracted when 30 g pot^?1 litter was applied and only 6% extracted at the higher litter rates. This suggests that the same problem of P buildup that has been reported in soils under pasture may also occur when poultry litter is repeatedly applied to the same soil planted to cotton. These results show that broiler litter not only supplied enough N but also supplied the four other macronutrients (P, K, Ca, and Mg) in amounts sufficient to support normal cotton growth. This research implies that poultry litter can effectively substitute for several fertilizers to meet crop macronutrient (N, P, K, Ca, and Mg) needs in soils deficient in any or all of these nutrients.     

Comparison of Chemical Methods of Assessing Potentially Available Organic Nitrogen from Organic Residues Applied to a Sandy Soil

Abstract

More than 90% of the nitrogen (N) in soils is bond as organic N compounds. The available N can be estimated on the mineral N released during time‐consuming incubations of soil. Several chemical methods have been developed as substitutes for incubations. On the other hand, there has been an increase in waste production. Residues could potentially offset the need for mineral fertilizers, being both an economic and environmental benefit. Thus, the development of a routine method for prediction of N supply both from soil organic matter (SOM) and the application of organic residues is of great interest. An incubation experiment was performed in a Cambic Arenosol to evaluate different chemical methods. Air‐dried soil was mixed with increasing amounts of composted solid municipal waste, secondary pulp‐mill sludge, hornmeal, poultry manure, the solid phase from pig slurry, and composted pig manure. Samples were incubated for 244 days under a controlled environment. Among the chemical extractants studied, hot 2 M potassium chloride (KCl) and hot 0.01 M calcium chloride (CaCl₂) showed promise in indicating values of N₀ (potentially available nitrogen), and these simple methods are suitable for use in routine laboratory conditions.     

Nitrogen Mineralization as Influenced by Different Organic Manures in an Inceptisol in the Foothill Himalayas

Nitrogen-use efficiency can be enhanced through an understanding of the nitrogen (N) mineralization behavior of organic sources. An incubation study was conducted to assess the impact of organic manures on N mineralization. The manures, farmyard manure (FYM), Leucaena leucocephala, and poultry manure, were applied to the soil alone or along with urea. There was a rapid increase in the amount of mineral N released with a peak appearing either at 14 days (+urea treatments) or 21 days (manure only) of aerobic incubation. Thereafter the net N mineralized decreased gradually and levelled off beyond day 56. Overall the cumulative net N mineralized after 98 days of incubation was in the order urea > Leucaena + urea > poultry manure + urea _> FYM + urea > Leucaena > poultry manure > FYM > zero N. The potentially mineralizable N (N₀) was lower in treatments where urea was not applied.