Soil Physical Properties and Organic Matter Fractions Under Forages Receiving Composts,Manure or Fertilizer

A field study was conducted to assess the benefits, with respect to soil physical properties and soil organic matter fractions of utilizing composts from a diversity of sources in perennial forage production. A mixed forage (timothy-red clover (Trifolium pratense L.) and monocrop timothy (Phleum pratense L.) sward were fertilized annually with ammonium nitrate (AN) at up to 150kg and 300 N ha^?1 yr^?1, respectively, from 1998-2001. Organic amendments, applied at up to 600 kg N ha^?1 yr^?1 in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC) or sewage sludge (SSLC), plus liquid dairy manure (DM), and supplied C to soil at 4.6 and 9.2 (CSC), 10.9 (SSLC), 10.0 (DMC) 2.9 (DM) Mg C ha^?1. Soil samples (0-5cm; 5-10cm;10-15cm) were recovered in 2000 and 2001. Improvements in soil physical properties (soil bulk density and water content) were obtained for compost treatments alone. Composts alone influenced soil C:N ratio and substantially increased soil organic carbon (SOC) concentration and mass (+ 5.2 to + 9.7 Mg C ha^?1). Gains in SOC with AN of 2.7 Mg C ha^?1 were detectable by the third crop production year (2001). The lower C inputs, and more labile C, supplied by manure (DM) was reflected in reduced SOC gains (+ 2.5 Mg C ha^?1) compared to composts. The distribution of C in densiometric (light fraction, LF; >1.7 g cm^?3) and particulate organic matter (POM; litter (>2000μm); coarse-sand (250-2000μm); fine-sand (53-250μm) fractions varied with compost and combining fractionation by size and density improved interpretation of compost dynamics in soil. Combined POM accounted for 82.6% of SOC gains with composts. Estimated compost turnover rates (k) ranged from 0.06 (CSC) to 0.09 yr^?1 (DMC). Composts alone increased soil microbial biomass carbon (SMB-C) concentration (μg C g^?1 soil). Soil available C (C_ext) decreased significantly as compost maturity increased. For some composts (CSC), timothy yields matched those obtained with AN, and SOC gains were derived from both applied-C and increased crop residue-C returns to soil. A trend towards improved C returns across all treatments was apparent for the mixed crop. Matching composts of varying quality with the appropriate (legume/nonlegume) target crop will be critical to promoting soil C gains from compost use.     

Optimal Acidity Indices for Soybean Production in Brazilian Oxisols

Soybean is an important crop for the Brazilian economy, and soil acidity is one of the main yield-limiting factors in Brazilian Oxisols. A field experiment was conducted during three consecutive years with the objective to determine soybean response to liming grown on Oxisols. Liming rates used were 0, 3, 6, 12, and 18 Mg ha^?1. Liming significantly increased grain yield in a quadratic trend. Ninety percent maximum economic grain yield (2900 kg ha^?1) was achieved with the application of about 6 Mg lime ha^?1. Shoot dry weight, number of pods per plant, and 100-grain weight were also increased significantly in a quadratic fashion with increasing liming rate from 0 to 18 Mg ha^?1. These growth and yield components had a significant positive association with grain yield. Maximum contribution in increasing grain yield was of number of pods per plant followed by grain harvest index and shoot dry weight. Uptake of nitrogen (N) was greatest and phosphorus (P) was least among macronutrients in soybean plant. Nutrient-use efficiency (kg grain per kg nutrient accumulation in grain) was maximum for magnesium (Mg) and lowest for N among macronutrients. Application of 3 Mg lime ha^?1 neutralized all aluminum ions in soil solution. Optimal acidity indices for 90% of maximum yield were pH 6.0, calcium (Ca) 1.6 cmol_c kg^?1, Mg 0.9 cmol_c kg^?1, base saturation 51%, cation exchange capacity (CEC) 4.8 cmol_c kg^?1, Ca/Mg ratio 1.9, Ca?/?potassium (K) ratio 5.6, and Mg/K ratio 3.0.     

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.     

Forage quality and yield increments of intensive managed grassland in response to combined sulphur-nitrogen fertilization Dedicated to Prof. em.Dr. Alois Kornher on his 75th birthday.

Abstract

A three-year experiment was carried out at three different sites in northern Germany to investigate the effects of combined sulphur (S, up to 50 kg S ha^?1 year^?1) and nitrogen (N, up to 300 kg N ha^?1 year^?1) fertilization on dry matter (DM) yield and forage quality. There was an interaction effect of site, year, S and N fertilization. The greatest DM yield increment relative to yield at the start of the experiment (1997) with no S and N applied was 10.2 t DM ha^?1 at Ostenfeld (arable grassland). Cattle slurry when applied to provide 50 kg N ha^?1 and 10 kg S ha^?1 did not noticeably increase yield. The S content in forage decreased significantly over the years without S fertilization. At 300 kg N ha^?1 and 0 kg S ha^?1, crude protein (CP) contents achieved 173 g kg^?1 DM and were diluted due to higher DM yields with S fertilization. The true protein content (TP% of CP) differed significantly at 300 kg N ha^?1. TP achieved 93% with 50 and 87% with 0 kg S ha^?1 year^?1, respectively. In conclusion, with N fertilizer intensities in the range of 300 kg N ha^?1, it is necessary to apply 25 kg S ha^?1 to improve forage yield and quality. On the other hand, with N fertilization levels below 300 kg N ha^?1, S fertilization could be omitted.     

Overwinter Mineralization of a Biosolid and Composted Banana Residues in Humid Mediterranean Conditions

The objectives of this work were to study nitrogen (N) release from a biosolid and a compost of banana wastes. The overwinter N decomposition was evaluated as the uptake by a cereal cover crop and the in situ losses from buried bags in a loamy sand (site 1) and in a calcareous silty clay loam (site 2). Organic materials were applied in two rates as sludge (1, 3.75 Mg ha^?1; 2, 7.5 Mg ha^?1) and compost (1, 3.29 Mg ha^?1; 2, 6.58 Mg ha^?1). Immediately after their incorporation in October, barley was planted as a cover crop. Its growth was negatively affected by the slow drainage of the silty clay loam, leading to greater N concentration in site 1 (21.18 g kg^?1 of barley versus 14.35 g kg^?1 of barley in site 2). Yet only 10% of the added N was intercepted by the cover crop in the fast-draining site 1. The ash-rich compost (N: 21.1 g kg^?1; ash: 467 g kg^?1) was comparable to the control. Within site 2, the biosolid treatments had a residual effect on a second barley crop, as N uptake was 1.99–2.13 times that of the control. The approach of in situ loss from bags incorporated in bare soil was repeated in two successive seasons. Nitrogen losses (% input) during the fall and winter months were comparable between sites 31.9 % (site 1) and 28.6 % (site 2). When the N fate was studied during the winter months only, the loss decreased slightly, suggesting the presence of a fraction liable to decomposition overwinter in Mediterranean conditions. Soil nitrate was determined 1 month after the incorporation of the cover crop in late spring. In the first season, only the sludge 2 treatment generated more nitrate than the control, whereas 19 months after the application of the organic products both sludge treatments had a positive effect. The soil properties influenced the amounts of N mineralized with site 1, yielding twice that of site 2. In the fast-draining soils, the presence of an active cover crop overwinter is necessary, while the N level of sludge 1 (164 kg N ha^?1) was more acceptable.     

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.     

Leaching of mineral nitrogen in the soil influenced by addition of compost and N-mineral fertilizer

This paper deals with the problem of mineral N leaching from arable lands due to the fertilization method. The influence of different doses of compost (50 and 100?Mg ha^?1) and N-mineral fertilizer (35-70-140 kg N ha^?1) on leaching of N_min in a lysimetric experiment with winter wheat. The area of our interest represents the main source of drinking water for the city of Brno and its neighborhoods. To demonstrate the effect of compost and mineral nitrogen addition, the lysimetric experiment was established there. Seven variants of the experiment with different fertilization schemes were studied during two vegetation seasons (2013 and 2014), each with three repetitions. The experiment was carried out in plastic experimental containers of 0.3 m diameter and 0.5 m height. Therefore, each lysimeter was the same size and was filled with 25 kg of subsoil and 25 kg of topsoil. The highest leaching of N_min was detected in the variant C2 where 140 kg N ha^?1 was applied, in both vegetation periods (5.97 kg N_min ha^?1 after the first vegetation period and 17.02 kg N_min ha^?1 after the second vegetation period). The positive effect of compost application (individually or in combination with the mineral N) on decrease in mineral N leaching was found during both vegetation period in comparison with variant C2. The highest doses of compost (100?Mg per ha) significantly decreased the concentration of mineral nitrogen in the soil eluate in both periods (3.03 kg N_min ha^?1 and 5.79 kg N_min ha^?1, respectively), by 197% and 293% in comparison with variant C2. There is evidence that the application of compost has a positive effect on the reduction of N_min leaching.     

Leaching of Nitrate,Ammonium, and Phosphate From Compost Amended Soil Columns

Compost amendment to agricultural soils has been reported to reduce disease incidence, conserve soil moisture, control weeds, or improve soil fertility. Application rate and placement of compost largely depends on the proposed beneficial effects and the rate may vary from 25 to 250 Mg ha^?1 (N content up to 4 percent). Application of high rates of compost with high N or P levels may result in excessive leaching of nitrate, ammonium, and phosphate into the groundwater. Leaching could be a serious concern on the east coast of Florida with its inherent high annual rainfall, sandy soils and shallow water table. In this study, five composts (sugarcane filtercake, biosolids, and mixtures of municipal solid wastes and biosolids) were applied on the surface of an Oldsmar sand soil (in 7.5 cm diameter leaching columns) at 100 Mg ha^?1 rate and leached with deionized water (300 ml day^?1, for five days; equivalent to 34 cm rainfall). The concentrations of NO₃-N, NH₄-N, and PO₄-P in leachate reached as high as 246, 29, and 7 mg L^?1, respectively. The amount of N and P leached accounted for 3.3-15.8 percent of total N and 0.2-2.8 percent of total P in the compost. The leaching peaks of NO₃-N occurred following the application of only 300-400 ml water (equivalent to 6.8-9.1 cm rainfall).     

Reducing Nitrogen Leaching from Agriculture: An Essential Step toward Protecting the Environment in High Rainfall Areas of Taiwan

ABSTRACT

Reducing nitrogen (N) leaching from croplands is important to protect environmental quality and improve recovery of applied N. To contribute to this broader goal of nutrient management, a simple pot experiment evaluated the potential differences among urea (250 kg N ha^?1), urea+compost (125 kg N ha^?1 from urea + 125 kg N from 8 Mg ha^?1 of compost), compost (250 kg N from 16 Mg ha^?1 of compost) and a zero control (Ctrl), in terms of their effects on apparent N recovery (ANR), mineral N (N_min) leaching and soil retention of applied N. Cabbage (Brassica oleraceae L.) and corn (Zea mays L.) were grown in rotation where compost application was not repeated in the 2nd year. N_min leaching was monitored by adding 83 mm and 62 mm of water fortnightly to cabbage and corn crops, respectively for a total of 28 times in a two-year period. Combined (urea+compost) and independent (compost) treatment application retained 1.5 to 2 times higher N, and lowered 2.1 to 4.6 times N_min leaching, relative to independent (urea) application. We conclude that farmers’ practice of fertilization that has an inherent problem of N leaching for high rainfall areas in Taiwan could be improved by proper compost and urea combinations within agronomically recommended rates of N application.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

Nitrogen rate and cultivar effects on nitrogen and nitrate concentration of sweet potato leaf tissue

Abstract

Nitrogen applications to dallisgrass grown on Olivier silt loam, an Aquic Fragiudalf, increased forage yield, forage digestibility, nutrient concentrations and nutrient contents as N rates increased to 896 kg ha^‐1. Expressing yield as a function of N application rate resulted in quadratic prediction equations that accounted for 75 to 98% of the variability in yield during five years. Eighty‐six percent of the maximum yield was obtained during the five years at 448 kg of N ha^‐1. Plant concentrations of N, Ca and Mg were increased more than concentrations of the other macronutrients as N rates increased. Plant contents of N, Ca and Mg in the forage increased 4.0, 3.2 and 3.5‐fold as N rates increased to 448 kg ha^‐1, while that of P, K and S increased 2.5 to 2.8‐fold. Residual N accumulations in the soil profile were apparent at the 896 kg ha^‐1 rate at the end of the growing seasons but were not detected the following March, indicating N losses by leaching and/or denitrification occurred at that N rate. Phosphorus applications increased forage P concentrations but did not increase forage yield nor available P levels in the surface 15 cm of soil. Maximum yields were obtained at forage P concentrations and Bray No. 2 soil P levels as low as 2.0 g kg^‐1 and 17 mg kg^‐1, respectively.     

Partitioning the Nutrient and Nonnutrient Contributions Of Compost to Dryland-Organic Wheat

Organic materials supply nutrients to plants but may also have other, nonnutrient-related benefits which are more difficult to quantify. This study partitioned the winter wheat (Triticum aestivum L.) yield response from compost applications into nutrient and nonnutrient fractions. Composted dairy manure and wheat straw bedding was applied at five rates (0, 10, 25, 50, and 75 Mg dry weight ha^?1) to dry-land wheat in an organic wheat-fallow farming system. The compost was fall-applied and incorporated prior to planting at adjacent sites in sequential years. Maximum grain yield increases from compost application ranged from 2,139 kg ha^?1 in a year with 186% of average annual precipitation to 1,324 kg ha^?1 in a year with 87% of average annual precipitation. The Mitscherlich equation was used to describe the yield response to compost rate. The nutrient and nonnutrient contributions of compost to grain yield were partitioned by solving the Mitscherlich equation for compost rates where applied nutrients were in surplus (≥25 Mg ha^?1), calculating a non-nutrient Mitscherlich response function, and subtracting the nonnutrient response function from the full response to determine the nutrient contribution across compost rates. At the 10 Mg ha^?1 compost rate, the nonnutrient to nutrient yield response ratio varied from 0.25:1 for the year with above average precipitation to 2.2:1 for the year with below average precipitation. Compost significantly increases dry-land wheat yields. These results suggest that nonnutrient benefits of compost applications may be significant and exceed nutrient benefits under dryland production in low rainfall years.     

Interactive Effect of Phosphorus and Nitrogen on Leaf Anthocyanins,Tissue Nutrient Concentrations,and Dry‐Matter Yield of Floralta Limpograss during Short Day Length

Abstract

A field trial was conducted during the short‐day period of 2004–2005 at Ona, Fl., to study the factorial effect of nitrogen (67, 90, and 134 kg N ha^?1) and phosphorus (0, 5, 10, 20, and 40 kg P ha^?1) rates on forage dry‐matter yield, quality, nutrient uptake, and leaf pigment concentration of limpograss (Hemarthria altissima). The N and P fertilizers were applied 45 days before each of two harvests. There was no interaction between N and P rates on any of the measured variables. Cool‐season forage yield increased curvilinearly from 137 to 350 kg ha^?1 in winter and 237 to 1389 kg ha^?1 in early spring, whereas crude protein (CP) concentration increased from 145 to 158 g kg^?1, as P was increased from 0 to 40 kg ha^?1, but yield and CP were not affected by N rate. There was a decreasing linear relationship between leaf concentration of anthocyanins and P rate of application such that forage obtained with 0 kg P ha^?1 had 61% more leaf anthocyanins and purple pigmentation than with 40 kg P ha^?1. There was no effect of N on anthocyanins content. It was concluded that increased level of leaf anthocyanins was due to the cumulative stress from cool weather and lower plant‐tissue P levels, which resulted in reduced growth and yield of limpograss. In cool weather, P played a critical role in controlling leaf purple pigmentation and forage yield.     

Residual Effects of Novel versus Traditional Organic Amendments for Rain-fed No-till Barley: Yield,Nutrient Uptake,and N2O Emissions

Organic amendments recycle nutrients, but N₂O emissions are both environmental and agronomic concerns. We conducted a 4-year field experiment to determine no-till barley (Hordeum vulgare L.) yield and nutrient uptake and soil N₂O emissions following a single application of six amendment treatments: (1) no amendment (Check); (2) synthetic N fertilizer (Fert); (3) fresh beef cattle feedlot manure (ManureF); (4) beef cattle feedlot manure compost (CompostR); (5) beef cattle feedlot manure composted with cattle mortalities (CompostM); and (6) separated solids from anaerobically digested cattle feedlot manure (ADM). Barley grown in Year 1 (2006), Year 2 (2007), and Year 4 (2009) (with Year 3 (2008) under fallow) had higher grain yields from ManureF (4.73 Mg ha^?1) in Year 2 and ADM (6.30 Mg ha^?1) in Year 4 (p < 0.05) than other treatments. The grain N and P contents were not affected (p > 0.05), but N uptake over 3 years (112.8 kg N ha^?1 yr^?1), and P uptake in Year 1 (19.1 kg ha^?1 yr^?1) and Year 2 (14.3 kg ha^?1 yr^?1) from ManureF, were higher (p < 0.05×) than other treatments. The cumulative N₂O emissions from ManureF in Year 1 (1.488 kg N ha^?1) and from ADM in Year 2 (1.072 kg N ha^?1) were higher (p < 0.05) than other treatments while the fraction of applied N emitted as N₂O was small (0.00 to 0.79%) and not affected by treatment. However, the percentages of applied N emitted as N₂O from compost and ADM were similar to synthetic fertilizer and livestock manure.     

Effect of Nitrogen Fertilizer Rate and Harvest Season on Forage Yield,Quality, and Macronutrient Concentrations in Midland Bermuda Grass

Bermuda grass [Cynodon dactylon (L.) Pers.] is a major forage for grazing and hay production in the southern United States. The objectives of this study were to determine effects of nitrogen (N) fertilization rate (0, 112, 224, 336, and 448 kg ha^?1), split spring and summer applications of N at the 224 and 448 kg ha^?1 rates, and harvest periods (spring and summer) on forage yield, crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrients (TDN), and concentrations of phosphorus (P), potassium (K), magnesium (Mg), and calcium (Ca in Midland Bermuda grass. Data were collected from 2002 to 2008 as part of an ongoing, long-term soil fertility experiment in southern Oklahoma. Repeated measures analysis of these long-term data showed that forage yield responses to N rate varied with year and harvest time with up to 2.5-fold yield differences among years. Nitrogen fertilization increased CP, TDN, and macronutrient P and Mg and decreased ADF and NDF. Crude protein was increased by ≥50%, and ADF and NDF dropped by up to 25% with the greatest N rate. In general, split N applications did not affect forage yield but produced low-quality forage compared to single N application in spring. Split application of 448 kg N ha^?1 gave forage with CP, TDN, ADF, and NDF similar to the Bermuda grass receiving 336 or 448 kg N ha^?1 as a single application. Spring forage had better forage quality than summer harvests. While N fertilization increased forage Mg and P concentrations by more than 50% during both spring and summer, it had no effect or slight increased K and Ca concentrations. In the southern Great Plains, despite the weather-dependent variability in forage yield of Bermuda grass, N application increase forage quality.     

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

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

Long‐Term Application of Biosolids on Apricot Production

Abstract

The use and disposal of biosolids, or wastewater treatment sludge, as a fertilizer and soil amendment is becoming increasingly widespread. We evaluated the multiyear use of biosolids in apricot (Prunus armeniaca L.) production, grown on productive agricultural soils. Class A biosolids were initially applied annually at rates of 0, 1.9, 5.8, and 11.7 Mg · ha^?1 (dry basis) to a 2‐year‐old apricot orchard on the USDA‐ARS research site on the eastern side of the San Joaquin Valley, CA. These application rates provided estimated rates of 0 (control), 57, 170, and 340 kg total N · ha^?1 yr^?1, respectively. Compared to the control treatment, the applications of biosolids significantly increased soil salinity (electrical conductivity from 1:1 soil–water extract) and total concentrations of nutrients [e.g., calcium (Ca), magnesium (Mg), sulfur (S), phosphorus (P), zinc (Zn), and copper (Cu)] after 7 years but did not increase the concentrations of selected metals [cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), and lead (Pb)] between 0‐ and 60‐cm soil depths. Mean concentrations of total nitrogen (N) and carbon (C) in soils (0‐ to 15‐cm depth) ranged from a low of 1.3 g kg^?1 to a high of 5.2 g · kg^?1 and from 14.1 g · kg^?1 to 45.7 g · kg^?1 for the control and high biosolids treated soils, respectively.

Biosolids applications did not lead to fruit yield reductions, although fruit maturation was generally delayed and more fruits appeared at picking times at the high rate of application. Yellow fruits collected from all biosolids applications were significantly firmer than were fruit collected from control trees, and they had higher concentrations of Ca, potassium (K), S, iron (Fe), and Zn in the fruit. Among the fruit quality parameters tested, the juice pH, total acidity, and fruit skin color were not significantly affected by biosolids applications. Malic acid concentrations decreased most of the time, while citric acid concentrations increased with increasing rates of biosolids applications. Overall, our results suggest that nonindustrial biosolids applied at an annual rate at or less than 11.7 Mg N · ha^?1 (340 kg N · ha^?1) can be safely used for apricot production on sandy loam soils.     

Nitrogen application effects on forage sorghum production and nitrate concentration

Abstract

Forage sorghum (Sorghum bicolor (L.) Moench) is an important annual forage crop but prone to high nitrate concentration which can cause toxicity when fed to cattle (Bos taurus and Bos indicus). Two field experiments were conducted over six site-years across Kansas to determine the optimum nitrogen (N) rate for no-till forage sorghum dry matter (DM) yield and investigate the effect of N fertilization on sorghum forage nitrate content. A quadratic model described the relationship between sorghum DM and N rate across the combined site-years. Maximum DM yield of 6530?kg ha^?1 was produced with N application rate of 100?kg N ha^?1. The economic optimum N rate ranged from 55 to 70?kg N ha^?1 depending on sorghum hay price and N fertilizer costs. Crude protein concentration increased with N fertilizer application but N rates beyond 70?kg N ha^?1 resulted in forage nitrate concentrations greater than safe limit of 3000?mg kg^?1. Nitrogen uptake increased with N fertilizer application but nitrogen use efficiency and N recovery decreased with increasing N fertilizer rates. In conclusion, forage sorghum required 55–70?kg N ha^?1 to produce an economic optimum DM yields with safe nitrate concentration.     

Boron fertilization of Mediterranean aridisols improves lucerne (Medicago sativa L.) yields and quality

Abstract

Lucerne (Medicago sativa L.) is grown as a forage crop on many livestock farms. In calcareous soils in eastern Turkey, lucerne production requires boron (B) addition as the soils are naturally B deficient. Field experiments with four B-application rates (0, 1, 3, and 9 kg ha^?1 B) were conducted in 2005 and 2006 to determine the optimum economic B rate (OEBR), critical soil test and tissue B values for dry matter (DM) production for lucerne grown on B-deficient calcareous aridisols in eastern Turkey. Boron application increased yield at each site in both years of production. The OEBR and critical soil and tissue B content were not impacted by location. Averaged over the two years and three locations, the OEBR was 6.8 kg B ha^?1 with an average DM yield of 12.0 Mg ha^?1. The average soil B content at the OEBR was 0.89 mg kg^?1 while leaf and shoot tissue B content amounted to 51.8 and 35.5 mg kg^?1, respectively. Boron application decreased tissue calcium (Ca), zinc (Zn), and copper (Cu), and increased tissue nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), and manganese (Mn). Tissue and soil B increased without impacting yield at B levels up to 9 kg ha^?1. We conclude that 7 kg ha^?1 B is sufficient to elevate soil test B levels from 0.11 to 0.89 mg kg^?1 and overcome B deficiency at each of the sites in the study. Similar studies with different soils and initial soil test B levels are needed to conclude if these critical soil and tissue values can be applied across the region.     

Predicting Biosolids Application Rates for Dryland Wheat across a Range of Northwest Climate Zones

We evaluated dryland wheat (Triticum aestivum L.) response to biosolids applications in the inland Pacific Northwest and compared agronomic application rates predicted from yield curves with those predicted from Extension guidance. We applied biosolids rate treatments during the fallow year in 10 on‐farm experiments and determined grain yield, protein, and postharvest soil nitrate. Nitrogen (N) rates were calculated from Extension guidance and compared with biosolids agronomic rate estimates based on yield regressions generated for each site. Eight of the 10 sites had quadratic yield responses. The agronomic biosolids rate at the responsive sites averaged 315 kg ha^?1 more grain than the farmer inorganic N rate. At responsive sites, a mean biosolids application rate of 4.7 dry Mg ha^?1 (226 kg total N ha^?1) was required for 95% of maximum grain yield. Results showed that Extension fertilizer guidance together with calculations for biosolids available N gave reasonable estimates for biosolids application rates.