Apparent Use Efficiency of Nitrogen and Phosphorus from Litter Applied to Bermudagrass

More than 80% of broiler (chicken, Gallus gallus domesticus) litter produced annually is applied as a plant nutrient source, particularly for nitrogen (N) and phosphorus (P), to pastures. However, N losses during the process of litter N mineralization limit availability of N to crops. This study determined broiler litter N and P availability and apparent use efficiency (ANUE, APUE) to bermudagrass [Cynodon dactylon] during the first year after litter application. Treatments consisted of three litter rates (3.3, 6.6, and 13.2 Mg ha^?1), a commercial N fertilizer rate that provided 358 kg N ha^?1 as ammonium nitrate (NH₄NO₃), and an untreated control. Results showed bermudagrass dry-matter (DM) yield increased significantly with increase in litter rate. Commercial N fertilizer produced significantly greater DM yield than 3.3 and 6.6 Mg ha^?1 of litter but produced less DM yield than 13.2 Mg ha^?1 of litter. The overall average of ANUE from litter was 39% compared to the 59% from fertilizer. The mean litter N availabilities to bermudagrass during the first year after litter application were 48.5, 112.5, and 222 kg ha^?1, corresponding to the 3.3, 6.6, and 13.2 Mg ha^?1 litter rates, respectively. The overall mean of litter N mineralization, which was surface broadcast to bermudagrass plots during the first year, was 59.5% of the total litter N applied. The APUE, averaged across the rate and locations, was 13.6%, which was quite smaller than the ANUE of 39%. This finding of small APUE also validates the potential for P accumulation in soil after long-term animal manure application.     

Coniferous afforestation increases soil carbon in maritime sand dunes

Afforestation of grasslands can increase C sequestration and provide additional economic and environmental benefits. Pine plantations, however, have often been found to deplete soil organic C and trigger detrimental effects on soils. We examined soil characteristics under a 45-year-old Pinus radiata stand and under adjacent grassland on maritime dunes in temperate Argentina. Soil under the pine plantation had greater soil organic C (+93%), total N (+55%) and available P (+100%) concentrations than under grassland. Carbon was stored under the pinestand at an estimated mean accretion rate of 0.64 Mg ha^?1 y^?1. At 0- to 25-cm depth, soil C amounted to 61 Mg ha^?1 under pine and 27 Mg ha^?1 under grassland. Soil C accumulated more on dune slopes (35 Mg ha^?1 y^?1) than on ridges(29 Mg ha^?1 y^?1) and bottoms (12 Mg ha^?1 y^?1). Compared with the grassland, soil acidity, cation-exchange capacity, base losses (K > Ca = Mg) and C/N ratio increased under pine. Spatial heterogeneity in soil characteristics was greater under pine than under grassland. Such variability was non-systematic and did not support the ‘single-tree influence circle’ concept. Afforestation increased C in soil, forest floor and tree biomass in dunes with ustic climate regime.     

Impact of Animal Manure on Soil Chemistry,Mineral Nutrients,Yield, and Fruit Quality in ‘Golden Delicious’ Apple

ABSTRACT

Incorporating deep litter cow and deep litter poultry manures with the top 30-cm soil improved orchard soil chemistry, including nutrient availability, soil organic matter, electrical conductivity (EC), pH, cation exchange capacity (CEC) and biological activity in a ‘Golden Delicious’ apple (Malus domestica Bork) orchard in Zanjan, Iran. Application of deep litter cow manure at 30 t ha^?1 or deep litter poultry manure at 10 t ha^?1 resulted in a higher rate of nitrogen (N) release, and thus increased yield and fruit size, but decreased fruit color. The least leaf minerals were found in the untreated control trees. The control trees showed minor symptoms of N, iron (Fe), and magnesium (Mg) deficiencies during the following season. Positive correlation existed between the rate of manure applied and the content of soil organic matter (OM). The deep litter poultry manure at 10 t ha^?1 increased the soil K, Mg, calcium (Ca), ammonium-N, and EC levels.     

Poultry litter and tillage influences on corn production and soil nutrients in a Kentucky silt loam soil

Broiler chicken (Gallus gallus) manure, a rich source of plant nutrients, is generated in large quantities in southeastern USA where many row crops, such as corn (Zea mays L.), are also extensively grown. However, the use of broiler manure as an economical alternative source of nutrients for corn production has not been extensively explored in this region. This study was conducted to examine the use of broiler litter as a source of nutrients for corn production, as influenced by tillage and litter rate, and any residual effects following application. In addition, the consequence of litter application to soil test nutrient levels, particularly P, Zn and Cu, was explored. The treatments consisted of two rates of broiler litter application, 11 and 22 Mg ha⁻¹ on a wet weight basis, and one rate of chemical fertilizer applied under no-till and conventional tillage systems. Treatments were replicated three times in a randomized complete block design. Corn was grown with broiler litter and inorganic fertilizer applied to the same plots each year from 1998 to 2001. In 2002 and 2003, corn was planted no-till, but only N fertilizer was applied in order to make use of other residual litter nutrients. Soil samples were taken yearly in the spring prior to litter application and 4 years after the cessation of litter application to evaluate the status of the residual nutrients in soil. Two years out of the 4-year experiment, broiler litter application produced significantly greater corn grain yield than equivalent chemical fertilizer application and produced similar grain yield in the other 2 years. Corn grain yield was significantly greater under no-till in 1999, but significantly greater under conventional-till in 2000, and no difference between the two tillage systems were observed in 1998 and 2001. With 4 years of litter application, Mehlich-3 P increased from an initial 18 mg kg⁻¹ to 156 mg kg⁻¹ with 11 Mg ha⁻¹ litter and to 257 mg kg⁻¹ with 22 Mg ha⁻¹ litter. For every 6 kg ha⁻¹ of P applied in poultry litter Mehlich-3 P was increased by 1 mg kg⁻¹. Modest increases in Mehlich-3 Cu and Zn did not result in phytotoxic levels. This study indicated that an optimum rate of broiler litter as a primary fertilizer at 11 Mg ha⁻¹ applied in 4 consecutive years on a silt loam soil produced corn grain yields similar to chemical fertilizer under both no-till and conventional tillage systems and kept soil test P, Cu and Zn levels below values considered to be harmful to surface water quality or the crop.     

Evaluation of Compost for Use as a Soil Amendment in Corn and Soybean Production

The purpose of this research project was to 1) evaluate rate of compost application and 2) to compare compost with uncomposted raw material and inorganic fertilizer N application upon maize and soybean growth and productivity, and upon soil characteristics. During the first three years of the study, the source of uncomposted material and compost was food waste and ground newsprint. During years 4 to 9 of the study, the source of uncomposted material and compost was dairy cow manure and wood chips. Application rates in field site 1 were 0, 11.2, 22.4, 33.6 and 44.8 Mg ha^?1 compost, 44.8 Mg ha^?1 uncomposted material and 140 kg ha^?1 fertilizer N (as urea). Application rates in field site 2 were 0, 22.4, 44.8, 67.2 and 134.4 Mg ha^?1 compost, 134.4 Mg ha^?1 uncomposted manure and 180 kg ha^?1 fertilizer N (dry matter basis). The high rates of compost application significantly raised organic matter levels, and available P and K compared to inorganic fertilizer N. Uncomposted manure and increasing compost application rates significantly increased grain yield, number of kernels per plant and plant weight. Composting significantly reduced pathogen indicator bacteria concentrations. The data of this study suggest that on these high organic matter soils 22.4 Mg ha^?1 to 44.8 Mg ha^?1 are optimal compost application rates.     

Bio-organic Amendment of Udic Ustochrept Soil for Minimizing Yield Decline in Sugarcane Ratoon Crops under Subtropical Conditions

The effects of subsequent sugarcane ratooning on soil quality and the crop yields under four treatments [an absolute control (T0), application of recommended dose of nitrogen (N)–phosphorus (P)–potassium (K) (T1), application of sulfitation press mud (SPM), a sugar factory by-product (T2), and SPM along with Gluconacetobacter diazotrophicus (Gd, T3)] were evaluated for 7 years. In the control (T0) and NPK-fertilized (T1) plots, an increase in soil compaction (5.4%), decrease in infiltration rate (6.04%), lower microbial activities, and increased soil phenolic contents (72.4%) rendered the nutrients unavailable, leading to significant declines in the crop yields at the rate of 5.47 Mg ha^?1 y^?1 and 4.67 Mg ha^?1 y^?1, respectively. The crop yield declined from 53 kg ha^?1 in plant crop to 18 kg ha^?1 in the sixth ratoon crop under the absolute control. The rates of yield decline, however, were minimized in SPM (T2) and SPM + Gd (T3) plots to 3.54 and 3.51 Mg ha^?1 y^?1.     

Effect of biochar and phosphorus fertilizer application on soil fertility: soil physical and chemical properties

This study evaluated the effect of biochar and phosphorus fertilizer application on selected soil physical and chemical properties in two contrasting soil types: Rhodic Ferralsols (clay) in Thohoyandou and Leptic Cambisols (loamy sand) in Nelspruit, South Africa. Field experiments were conducted in summer and winter. Treatments consisted of a factorial combination of four biochar levels (0, 5, 10 and 20 t ha^?1) and two phosphorus fertilizer levels (0 and 90 kg ha^?1) arranged in a randomized complete block design with three replicates. Chickpea was the test crop. Soil bulk density, aggregate stability, porosity, total C, total N, C:N ratio, K and Mg were determined. Biochar (10 t ha^?1) and phosphorus increased bulk density and decreased porosity at 0–5 and 15–20 cm soil depth on a loamy sand soil in both seasons. The interaction between biochar and phosphorus increased total C and total N on a clay soil in the summer sowing. However, in the loamy sand soil, biochar (10 t ha^?1) increased total C, C:N ratio, K and Mg in the summer sowing. The effect of biochar was more evident in the loamy sand soil than the clay soil suggesting that the influence of biochar may be soil-specific.     

Long-term fertilizer trials on loam soil at M⊘ystad,south-eastern Norway: Crop yields,nutrient balances and soil chemical analyses from 1983 to 2003

Abstract

Factorial combinations of N, P and K fertilizer have been compared with the use of farmyard manure at M?ystad since 1922 in a seven-year crop rotation (3 ley, oat, potato, wheat, barley). Until 1982, low inputs of N fertilizer (22 kg ha^?1) were used. In 1983, they were brought into line with current farming practice. This paper presents the results of three subsequent rotations. Yields without any fertilizer were on average 48% of those with 100 kg N ha^?1 in compound fertilizer, whilst those with 20, 40 and 60 Mg ha^?1 farmyard manure were 81, 87 and 90%, respectively. Yields with other combinations of N, P and K declined in the order NP, NK, N, PK and K. When NPK fertilizer was used, apparent recoveries of applied fertilizer were close to 50% for N and K, and around 40% for P. Much lower values were found for nutrients applied singly. Balance between N supply and removal was indicated at rates of about 60 kg N fertilizer ha^?1 in potatoes, 75 kg ha^?1 in cereals and 90 kg ha^?1 in leys. A surplus of P was found in all crops at all N levels, and of K in cereals and potatoes. In leys, K balance was achieved with an N supply of 90 kg N ha^?1. Nutrient balance was indicated at a little below 20 Mg ha^?1 yr^?1 farmyard manure. Larger manure applications gave large nutrient surpluses, particularly of N. Soil reaction remained close to neutral with the use of calcium nitrate and manure, but declined with the use of ammonium nitrate. Manure use gave the highest amounts of available P, K and Mg in soil. Similar increases in total inorganic P were found with manure use as with fertilizer use, but amounts of organic P and total K were little affected.     

Influence of Long‐Term Application of Organic and Inorganic Fertilizer to Build Up Soil Fertility and Nutrient Uptake in Mint‐Mustard Cropping Sequence

Abstract

Field experiment was conducted for 7 years continuously to evaluate the influence of combined application of organic and inorganic fertilizer on soil fertility buildup and nutrient uptake in mint (Mentha arvensis) and mustard (Brassica juncea) cropping sequence. Maximum organic carbon was observed under full supply of organic manure (T₂; FYM at 20 t ha^?1) averaged across all the Stages of cropping sequence. It was increased by 38, 50, and 51% in T₂ in Stages I (after mint harvest/presowing of dhaincha), II (after incorporation of dhaincha (Sesbania aculeata)/presowing of mustard), and III (after harvest of mustard/preplanting of mint), respectively, over their respective controls. In general, magnitude of organic carbon was recorded higher in Stage II after green manuring of Sesbania compared with Stages I and III. Nitrogen availability in treated plots was increased by 26.0–89.9, 15.2–64.5, and 4.9–52.0% in Stages I (after mint harvest/presowing of Sesbania), II (after incorporation of dhaincha/presowing of mustard), and III (after harvest of mustard/preplanting of mint), respectively, over their respective control. Average across all the three Stages showed a positive balance of nitrogen (N), phosphorus (P), and potassium (K) in soil under different treatments. Mean of the three Stages indicated that maximum available N, P, and K were increased by 36.1, 129.0, and 65.20% in T₄ (N:P:K: 133:40:40 and FYM at 6.7 t ha^?1), T₄ (N:P:K::133:40:40 and FYM at 6.7 t ha^?1), and T₃ (N:P:K::100:30:30 and FYM at 10 t ha^?1), respectively, over their initial status. Supply of organic and inorganic fertilizer (T₄; N:P:K::133:40:40 and FYM at 6.7 t ha^?1) was found most suitable combination with respect to N, P availability in soil, and productivity of mint and mustard crop.     

Silvopasture Switchgrass Fertilized with Poultry Litter: Nutrient Removal,Soil Fertility,and Runoff Water Quality

Alternative use of poultry litter (PL) for forest rather than pasture fertilization would improve forest soil fertility and reduce nutrient build-up in pasture. Yield and nutrient uptake of Alamo switchgrass (Panicum virgatum L.) in a loblolly pine (Pinus taeda L.) silvopasture annually fertilized with PL or urea at 80 and 160 kg N ha^?1 for four years, and without fertilization were compared. Treatment effects on soil fertility and effect of PL on runoff water quality were also determined. Fertilization with N increased yields 120% to an average of 3.8 Mg ha^?1 yr^?1. Since nutrient removal was small, P, base cations and pH increased in the ≤30 cm depth soil with PL. Total P in edge-of-plot runoff was increased by 0.31 kg ha^?1 y^?1 at the higher PL rate. Two applications at this rate per tree rotation might be justified based on increased soil fertility and infrequently increased P load.     

Mineralization and Nutrient Release of an Organic Fertilizer Made by Flour,Meat, and Crop Residues in Two Vineyard Soils with Different pH Levels

The mineralization and nutrient evolution of an organic fertilizer compost of flour, meat, and crop residues was evaluated in two vineyard soils. A lysimetric testing, using 2.2-L Büchner funnels, was carried out to study the evolution of pH, electrical conductivity, and nutrients during the 400-day experiment. The net mineralization for two different doses of the fertilizer mixed with the soils was compared with an unfertilized control. The pH value of the acidic soil decreased to values less than 4.5 because of the yield of hydrogen (H⁺) in the organic fertilizer mineralization, whereas the soluble aluminium (Al³⁺) increased quickly in the leachates. The mineralization process was quicker in the alkaline soil (with a maximum mineralization rate of 0.83 mg nitrogen (N) kg^?1 day^?1 for the 8 Mg ha^?1 dose and 0.43 mg N kg^?1 day^?1 for the 4 Mg ha^?1 dose) in comparison with the acidic soil, which reduced these rates up to 50%. The N-nitrate (NO₃) amounts yielded in a year were 150 and 79 kg N ha^?1 for the 8 and 4 Mg ha^?1 doses respectively in the alkaline soil, enough to cover the vineyard N demand. These values were reduced to 50% and 60% of N-NO₃ for the acidic soil, indicating the important effect of pH in the mineralization.     

Spring camelina N rate: balancing agronomics and environmental risk in United States Corn Belt

Camelina (Camelina sativa (L.) Crantz) seed oil has desirable properties for producing advanced biofuels and as a healthy cooking oil. It has been grown for centuries, but basic recommendations for nitrogen (N) fertilizer requirements are still needed to support widespread industrial cultivation across North America. A replicated N-response plot-scale study was conducted on a northern Mollisol soil for two growing seasons to 1) determine seed and oil yield, seed oil content, and vegetative response; 2) determine indices of N use efficiency; and 3) measure post-harvest residual inorganic soil N as an index of environmental risk. Seed and oil yield response to N fertilization was described with a quadratic function, which predicted maximum seed yield (1450 kg ha^?1) and oil yield (580 kg ha^?1) at about 130 kg N ha^?1. However, seed and oil yield did not differ significantly among N-rates above 34 kg N ha^?1. Seed oil content averaged 400 g kg^?1 among all N rates. Agronomic efficiency declined above 34 kg N ha^?1, which coincided with an increase of post-harvest soil nitrate-N plus ammonium-N (residual N). Considering N use efficiency, simple cost analysis, and risk associated with residual N, a rate of 34 kg N ha^?1 is recommended.     

Manure and nitrogen fertilizer effects on corn productivity and soil fertility under drip and furrow irrigation

A field experiment was conducted at the Arkansas Valley Research Center in 2005 through 2007 to study the effects of manure and nitrogen fertilizer on corn yield, nutrient uptake, N and P soil tests, and soil salinity under furrow and drip irrigation. Manure or inorganic N was applied in 2005 and 2006 only. There were no significant differences in corn yield between drip and furrow irrigation even though, on average, 42% less water was applied with drip irrigation. Inorganic N or manure application generally increased grain yield, kernel weight, grain and stover N uptake, and grain P uptake. Nitrogen rates above 67 kg ha^?1 did not increase grain yield significantly in 2005 or 2006, nor did manure rates in excess of 22 Mg ha^?1. High manure rates increased soil salinity early in the season, depressing corn yields in 2005 and 2006, particularly with drip irrigation. Salts tended to accumulate in the lower half of the root zone under drip irrigation. Residual nitrate nitrogen from manure and inorganic N application sustained corn yields above 12.0 Mg ha^?1 in 2007. More research is needed to develop best manure and drip irrigation management for corn production in the Arkansas Valley.     

Effects of organic fertilizers on yam productivity and some soil properties of a nutrient-depleted tropical Alfisol

Field experiments were conducted at Owo, southwest Nigeria to select organic fertilizer treatments most suitable for sustaining high soil fertility and yam productivity on a nutrient-depleted tropical Alfisol. Eight organic fertilizer treatments were applied at 20 t ha^?1 with a reference treatment inorganic fertilizer (NPK 15–15–15) at 400 kg ha^?1 and natural soil fertility (control), laid out in a randomized complete block design with three replications. Results showed that organic fertilizers significantly increased (p = 0.05) tuber weight and growth of yam, soil and leaf N, P, K, Ca and Mg, soil pH and organic C concentrations compared with the NSF (control). The oil palm bunch ash + poultry manure treatment increased tuber weight, vine length, number of leaves and leaf area of yam by 66, 25, 21 and 52%, respectively, compared with inorganic fertilizer (NPK) and 37, 22, 19 and 44%, respectively, compared with poultry manure alone. Sole or mixed forms of organic fertilizers showed significant improvement in soil physical conditions compared with IF (NPK) and NSF (control). Synergistic use of oil palm bunch ash + poultry manure at 10 t ha^?1 each was most effective for sustainable management of soils and for improving agronomic productivity of yam.     

Effect of Integrated Nutrition in Aromatic Rice on Carbon and Nutrient Status in an Inceptisol

Inorganic fertilizer-based nutrient management is the maintenance of soil fertility for sustaining increased crop productivity, but often at the cost of degrading soil health. This study was conducted to determine whether incorporation of organics in the conventional inorganic-based nutrient management practice on aromatic rice could sustain both fertility and soil organic carbon status on a silt loam Aeric Haplaquept. Addition of organic manure along with inorganic fertilizer could almost maintain organic carbon status of soil, while the treatment only with inorganic fertilizer registered a substantial decrease (6.58%) from its initial value. Among the treatment combinations, the treatment receiving 1 t ha^?1 mustard cake and inorganic fertilizer @ N₄₀P₂₀K₂₀ was the best, which registered the highest grain (3.01 t ha^?1) and straw (5.32 t ha^?1) yield of rice, highest nutrient uptake, and least decline in available N, P, and K status of soil. However, even the best treatment combination also was proved to be suboptimal in sustaining soil fertility.     

On-Site Assessment of Extractable Soil Nutrients after Long-Term Biosolid Applications to Perennial Forage

The objective of this study was to evaluate soil nutrient loading and depth distributions of extractable nitrogen (N), phosphorus (P), and potassium (K) after long-term, continuous annual surface applications of anaerobically digested class B biosolids at a municipal recycling facility in central Texas. Commercial forage production fields of coastal bermudagrass (Cynodon dactylon L.) were surface applied at 0, 20, 40, or 60 Mg dry biosolids ha^?1 y^?1 for 8 years. Application duration was evaluated in fields treated with 20 Mg dry biosolids ha^?1 y^?1 for 0, 8, or 20 years. Total soil loads of extractable inorganic N and P increased linearly with application rate, but only extractable P increased with duration. Neither total load nor soil distribution of extractable K was affected by biosolid applications. Mineralization of biosolid-derived organic N and P likely contributed to elevated concentrations of nitrate throughout the soil profile (0–110 cm) and orthophosphate in surface soils (0–40 cm).     

The inorganic N requirement,nodulation and yield of common bean (Phaseolus vulgaris L.) as influenced by inherent soil fertility of eastern Ethiopia

Though mineral N application impaired nodulation initiation and function, it improves the productivity of common bean. The effect of inorganic application on common bean productivity, however, is dependent on the availability of plant nutrients including nitrogen (N) in the soils. Therefore, multilocation field experiments were conducted at Babillae, Fedis, Haramaya, and Hirna to evaluate the effect of inherent soil fertility status on responsiveness of common bean to different rates of N fertilizer application and its effect on nodulation, yield, and yield components of common bean. The treatments were six levels of N fertilizer (0, 20, 40, 60, 80, and 100 kg N ha^?1) laid out in randomized completed block design with three replications. The result revealed that 20 kg N ha^?1 application significantly improved the nodule number (NN) and nodule dry weight (NDW) except Hirna site, in which reduction of NN and NDW was observed. Although the remaining investigated yield and yield components were significantly improved due to N fertilizer in all study sites, 40 kg N ha^?1 application resulted in significantly increased GY of common bean at Fedis, Haramaya, and Hirna site, while 60 kg N ha^?1 at Babillae site. The highest total biomass yield (7011.6 kg ha^?1) and GY (2475.28 kg ha^?1) of common bean were recorded at Hirna and Haramaya sites, respectively, indicating the importance of better fertile soil for good common bean production. Hence, it can be concluded that the effect of inorganic N on common bean was irrespective of soil fertility rather the total amount of N in soil would affect the need of different rate of inorganic N.     

Manure-Based Organic Soil Amendments Provide an Adequate Nutritional Source for Corn Production in Chile When Combined with Urea Applications

ABSTRACT

The use of manure-based organic soil amendments is common in countries with food animal production. A two-season field study was carried out in central Chile to evaluate the effect of different poultry litter (PL) and pig compost (PC) rates (7.5, 10.0, 12.5, and 15.0 Mg ha^?1for each amendment) combined with different nitrogen (N) rates (0, 100, 200, and 300 kg ha^?1) on dry matter (DM), grain production, and macronutrient concentration in corn (Zea mays L.) produced during the 2008–2009 (PL) and 2009–2010 (PC) seasons. The soil was clay loam. Organic amendments were applied before sowing, whereas inorganic N (urea) was applied at the 6-leaf stage (V6). When PL was combined with N, DM production ranged between 21.44 and 31.01 Mg ha^?1 and grain yield was between 12.76 and 17.86 Mg ha^?1. When PC was combined with N, DM production values were between 21.07 and 26.18 Mg ha^?1 and grain yield was between 14.01 and 17.14 Mg ha^?1. Results indicate that applying a combination of PL and N improved DM production, but applying a combination of PC and N did not affect this parameter. Grain production was only affected by increasing N rates. Applying both PL and N improved plant macronutrient concentration, while only applying PC increased N concentration. These results could be considered as the best recommended practices for using PL and PC.     

Impact of grazed grassland management on total N accumulation in soil receiving different levels of N inputs

Nitrogen balances and total N and C accumulation in soil were studied in reseeded grazed grassland swards receiving different fertilizer N inputs (100–500 kg N ha^?1 year^?1) from March 1989 to February 1999, at an experimental site in Northern Ireland. Soil N and C accumulated linearly at rates of 102–152 kg N ha^?1 year^?1 and 1125–1454 kg C ha^?1 year^?1, respectively, in the top 15 cm soil during the 10 year period. Fertilizer N had a highly significant effect on the rate of N and C accumulation. In the sward receiving 500 kg fertilizer N ha^?1 year^?1 the input (wet deposition + fertilizer N applied) minus output (drainflow + animal product) averaged 417 kg N ha^?1 year^?1. Total N accumulation in the top 15 cm of soil was 152 kg N ha^?1 year^?1. The predicted range in NH₃ emission from this sward was 36–95 kg N ha^?1 year^?1. Evidence suggested that the remaining large imbalance was either caused by denitrification and/or other unknown loss processes. In the sward receiving 100 kg fertilizer N ha^?1 year^?1, it was apparent that N accumulation in the top 15 cm soil was greater than the input minus output balance, even before allowing for gaseous emissions. This suggested that there was an additional input source, possibly resulting from a redistribution of N from lower down the soil profile. This is an important factor to take into account in constructing N balances, as not all the N accumulating in the top 15 cm soil may be directly caused by N input. N redistribution within the soil profile would exacerbate the N deficit in budget studies.     

Eucalyptus biochar application enhances Ca uptake of upland rice,soil available P,exchangeable K,yield, and N use efficiency of sugarcane in a crop rotation system

It was hypothesized that the application of eucalyptus biochar enhances nutrient use efficiencies of simultaneously supplied fertilizer, as well as provides additional nutrients (i.e., Ca, P, and K), to support crop performance and residual effects on subsequent crops in a degraded sandy soil. To test this hypothesis, we conducted an on‐farm field experiment in the Khon Kaen province of Northeastern Thailand to assess the effects of different application rates of eucalyptus biochar in combination with mineral fertilizers to upland rice and a succeeding crop of sugarcane on a sandy soil. The field experiment consisted of three treatments: (1) no biochar; (2) 3.1 Mg ha^?1 biochar (10.4 kg N ha^?1, 3.1 kg P ha^?1, 11.0 kg K ha^?1, and 17.7 kg Ca ha^?1); (3) 6.2 Mg ha^?1 biochar (20.8 kg N ha^?1, 6.2 kg P ha^?1, 22.0 kg K ha^?1, and 35.4 kg Ca ha^?1). All treatments received the same recommended fertilizer rate (32 kg N ha^?1, 14 kg P ha^?1, and 16 kg K ha^?1 for upland rice; 119 kg N ha^?1, 21 kg P ha^?1, and 39 kg K ha^?1 for sugarcane). At crop harvests, yield and nutrient contents and nitrogen (N) use efficiency were determined, and soil chemical properties and pH₀ monitored. The eucalyptus biochar material increased soil Ca availability (117 ± 28 and 116 ± 7 mg kg^?1 with 3.1 and 6.2 Mg ha^?1 biochar application, respectively) compared to 71 ± 13 mg kg^?1 without biochar application, thus promoting Ca uptake and total plant biomass in upland rice. Moreover, the higher rate of eucalyptus biochar improved CEC, organic matter, available P, and exchangeable K at succeeding sugarcane harvest. Additionally, 6.2 Mg ha^?1 biochar significantly increased sugarcane yield (41%) and N uptake (70%), thus enhancing N use efficiency (118%) by higher P (96%) and K (128%) uptake, although the sugar content was not increased. Hence, the application rate of 6.2 Mg ha^?1 eucalyptus biochar could become a potential practice to enhance not only the nutrient status of crops and soils, but also crop productivity within an upland rice–sugarcane rotation system established on tropical low fertility sandy soils.