Soil audit of a long-term phosphate experiment in south-western Victoria: total phosphorus, sulfur, nitrogen, and major cations

2000 ◽  
Vol 51 (6) ◽  
pp. 737 ◽  
Author(s):  
M. R. McCaskill ◽  
J. W. D. Cayley
Keyword(s):  
Soil Profile ◽  
Water Movement ◽  
Soil Layer ◽  
Fertility Treatment ◽  
High Fertility ◽  
Single Superphosphate ◽  
Soil P ◽  
Total Soil ◽  
Western Victoria

A nutrient audit was conducted on a long-term grazed fertiliser experiment at Hamilton in south-western Victoria to determine the fate of applied phosphorus (P) and sulfur (S). Single superphosphate had been applied at rates averaging between 1 and 33 kg P/ha.year since the start of the experiment in 1977. Soil samples were taken in 1994 by coring to a depth of 80 cm, and analysed for total soil nutrient concentration. Most (80%) applied P was in the top 43 cm of the soil profile. A further 6.5% had been transferred to sheep camp areas and 6.5% had been exported as product. It was estimated that <0.4% of applied P left the site in surface water movement. Unaccounted P (6.6%) was probably in the soil, but could not be detected because of the relatively wide confidence margin for total soil P. Only 31% of applied S was detected in the top 43 cm, 3.6% had been transferred to sheep camps, and 4.9% exported in product. Unaccounted S (60%) had probably moved deeper into the soil where it could not be detected from background levels of total soil S. Bulk density in the 0–5-cm layer increased by 1% for each additional ewe per ha, but decreased by up to 0.4% for each kg/ha.year of P fertiliser. Soil nitrogen (N) accumulated at 46 kg N/ha.year at the highest P application rate.Differences in total potassium (K) between low and high fertility treatments indicated that 20 kg K/ha.year had moved out of the 5–19-cm soil layer of the high fertility treatment. This was attributed to competition for exchange sites from calcium (Ca) in the superphosphate. It was concluded that fertilisers with a higher P : S ratio and a lower Ca content than superphosphate are more appropriate for the basalt-derived duplex soils because they would reduce problems associated with displacement of K in the soil profile.

Available phosphorus, sulfur, potassium, and other cations in a long-term grazing experiment in south-western Victoria

2002 ◽  
Vol 53 (12) ◽  
pp. 1349 ◽  
Author(s):  
J. W. D. Cayley ◽  
M. R. McCaskill ◽  
G. A. Kearney
Keyword(s):  
Nutrient Status ◽  
Grazing Pressure ◽  
Available Phosphorus ◽  
Plant Responses ◽  
Single Superphosphate ◽  
Soil P ◽  
Olsen P ◽  
Western Victoria ◽  
Stocking Rates

Relationships between amounts of superphosphate applied to pasture and stocking rate on available nutrient status were assessed from 1979 to 2000 on a chromosol derived from basalt at Hamilton, Victoria. The pastures were stocked with sheep at low, medium, or high grazing pressures in factorial combination with 6 levels of superphosphate. Overall annual amounts of single superphosphate (8.8% P, 11% S, 19% Ca) applied ranged from 0.4 to 36 kg P/ha. Potassium chloride (KCl) was applied to all plots periodically. Average stocking rates ranged from 7 to 19 dry sheep equivalents (DSE)/ha. The nutrient status of plots was monitored by sampling the soil to a depth of 10 cm, avoiding the areas used by the sheep for camping. In 1994, samples of topsoil (0–5 cm and 5–10 cm) were taken from the camp areas and non-camp areas in each plot in order to assess 'plant-available' P, S, and extractable cations. Changes in P and S with depth to 80 cm in high and low grazing pressure treatments were also assessed. The influence of cumulative P applied on Olsen P varied with time and grazing pressure. During the first 12–15 years, the Olsen P of high grazing pressure plots was greater than that of low grazing pressure plots, but subsequently the reverse has been the case. Plant-available S also increased where more superphosphate had been applied. Levels were greater than 7 mg S/kg soil except at the lowest level of superphosphate, indicating that forms of P fertiliser with less S could be used here. After initial applications of KCl, this fertiliser was not applied for 8 years. During this time the K status fell from 270 to 120 mg K/kg soil, just above where plant responses to K are likely, emphasising the need to monitor the K status of productive pastures on these soils. Levels of exchangeable Mg2+ fell as more superphosphate was used, whereas levels of Ca2+ rose. The Olsen P of soil deeper than 10 cm was always less than 5 mg P/kg soil. P supply to deep-rooted pasture plants may thus be limiting when the topsoil is dry. These results, together with published assessments of animal production at this site, show that for pastures fertilised annually, the Olsen P associated with the most profit varied from 7 mg P/kg soil at 7 ewes/ha (10.5 DSE/ha), to 14 mg P/kg soil at 18 ewes/ha.

Molecular Speciation of Phosphorus in Soil Under Various Long-Term Fertilization Regimes

2021 ◽  
Author(s):  
Xue Li ◽  
Qiuxiang Wen ◽  
Shiyu Zhang ◽  
Na Li ◽  
Jinfeng Yang ◽  
...  
Keyword(s):  
Plant Growth ◽  
Soil Layer ◽  
Growth And Yield ◽  
Pig Manure ◽  
Corn Yield ◽  
Key Factors ◽  
Mineral Fertilization ◽  
Soil P ◽  
N Fertilizers

Abstract Aims The objectives of this study were to examine the long-term substitution of mineral phosphorus (P) fertilizers with manure (M) plus nitrogen (N) fertilizers and how they affect the forms of P that occur in soil, soil P distribution, and plant growth.Methods We used a solution of 31P nuclear magnetic resonance (31P-NMR) spectroscopy to study the correlations between long-term fertilization regimes and the forms of P that occur at different soil depths. Then we investigated yield, plant growth, and soil properties.Results A 40-year field experiment showed that the use of M + N fertilizers can significantly improve plant growth and yield. The proportion of organic P in the 20-40 cm soil layer was significantly increased by long-term M fertilization. The concentrations of various forms of P (orthophosphate, pyrophosphate, diesters, monoesters, and total inositol hexakisphosphate, IHP) in topsoil increased significantly with the combination of M with N + P mineral fertilization. The addition of M greatly increased the stereoisomers of IHP (myo-IHP, scyllo-IHP, neo-IHP, and D-chiro-IHP) and the proportion and concentration of corrected diesters. There were no significant differences in the pyrophosphate contents of the 40-60 cm soil layer according to fertilization type and year of fertilization. There were also no significant differences in IHP stereoisomers and diesters according to fertilization year. The P forms that contributed to corn yield were orthophosphate, diester, and IHP. Further, pyrophosphate made no significant contribution to corn growth. Conclusions Over the long-term, pig manure can significantly increase the amount of orthophosphate that is directly absorbed by crops and the amount of IHP stereoisomers that can be used by plants. Orthophosphate and IHP are the two key factors that have a positive effect on plant growth.

EFFECT OF EXCESS FEEDLOT MANURE ON CHEMICAL CONSTITUENTS OF SOIL UNDER NONIRRIGATED AND IRRIGATED MANAGEMENT

1986 ◽  
Vol 66 (2) ◽  
pp. 303-313 ◽  
Author(s):  
J. F. DORMAAR ◽  
T. G. SOMMERFELDT
Keyword(s):  
Organic Matter ◽  
Chemical Constituents ◽  
Soil C ◽  
Soil P ◽  
Total Soil ◽  
Labile Phosphorus ◽  
Moisture Regimes ◽  
Labile P ◽  
Recommended Level

A long-term field experiment was initiated in 1973 to determine the safe loading capacity of a Lethbridge loam (Dark Brown Chernozemic) with feedlot manure. The effect of 10 yr of feedlot manure loading was examined by analyzing a number of inorganic and organic matter constituents of the Ap horizon. Although soil C, P, and enzyme activities increased as feedlot manure additions to the soil increased, these increases diminished at triple the recommended loading regimes. Phosphatase activity was checked by increased labile phosphorus levels. Levels of adenosine 5′-triphosphate increased but fluctuated with time under various moisture regimes. The C:N ratios, percent monosaccharide C of total soil C, and the ratio of deoxyhexoses to pentoses remained constant while the percentage of manure C retained decreased as feedlot manure loading increased. The distribution between pentoses and hexoses was strongly affected by feedlot manure levels while the deoxyhexose percentage of the sum of the eight monosaccharides determined remained about the same. Feedlot manure additions, at triple the recommended level, increased the labile P as a percentage of total soil P to around 50%. Although mineralization did not keep pace with the quantities applied, the presence of undecomposed manure did not seem to have harmful agronomic effects. Key words: ATP, feedlot manure, labile phosphorus, monosaccharides, organic matter

Phosphorus fertilizer for nitrogen fertilized dairy pastures. 1. Long term effects on pasture, diet and soil

1997 ◽  
Vol 129 (2) ◽  
pp. 205-217 ◽  
Author(s):  
T. M. DAVISON ◽  
W. N. ORR ◽  
B. A. SILVER ◽  
R. G. WALKER ◽  
F. DUNCALFE
Keyword(s):  
N Fertilizer ◽  
Panicum Maximum ◽  
Phosphorus Fertilizer ◽  
Long Term Effects ◽  
Single Superphosphate ◽  
Soil P ◽  
P Fertilizer ◽  
Autumn And Winter ◽  
Extractable Soil

The phosphorus fertilizer requirements and long term productivity of nitrogen-fertilized Gatton panic (Panicum maximum cv. Gatton) pastures, grazed by lactating dairy cows, were evaluated over 7 years. Cows grazed at 2·6 cows/ha on pastures that received annually 100 or 300 kg N/ha at each of 0, 22·5 or 45 kg P/ha. Phosphorus treatments were applied as single superphosphate, balanced for calcium by applications of gypsum.The soil had an initial available soil phosphorus content of 40 mg/kg (bicarbonate extraction). At zero P fertilizer (0P), extractable soil P declined at the rate of 1·9 mg/kg each year; at 22·5P it was maintained close to the original level while at 45P it increased at 6·6 mg/kg each year. Increased P fertilizer caused significant (P<0·01) increases in plant P concentration from year 2 onwards. In years 6 and 7 there was significantly less green pasture and leaf on offer in 300N pastures at 0P than with 22·5P and 45P. There was no influence of rate of P fertilizer at 100N on pasture quantity on offer in any year. There were clear trends at 100N of decreasing total pasture and green dry matter (DM) on offer over the 7 years, but not at 300N.Cows at 300N consumed more leaf in the diet in autumn and winter than at 100N. Leaf was 55–60% of the diet in summer and autumn, but decreased to 21% (100N) and 37% (300N) in winter. Dead material in the diet was always higher at 100N. Pasture leaf percentage and leaf yield were the best individual predictors of leaf percentage in the diet. Diet P selected from pasture was reduced by the higher rate of N fertilizer in each season. Estimated P concentrations of the diet selected from pasture for summer, autumn and winter averaged 0·30, 0·38 and 0·28% DM for 100N and 0·19, 0·24 and 0·18% DM for 300N treatments, respectively.The response to P fertilizer was dependent on the rate of N fertilizer applied. The critical bicarbonate extractable soil P level for this soil type, below which pasture responses occurred, was 30 mg/kg at 300N. The critical level at 100N was not reached, but was <23 mg/kg P.

scholarly journals Forms and accumulation of copper and zinc in a sandy typic hapludalf soil after long-term application of pig slurry and deep litter

2013 ◽  
Vol 37 (3) ◽  
pp. 812-824 ◽  
Author(s):  
Tadeu Luis Tiecher ◽  
Carlos Alberto Ceretta ◽  
Jucinei José Comin ◽  
Eduardo Girotto ◽  
Alcione Miotto ◽  
...  
Keyword(s):  
Soil Profile ◽  
Surface Soil ◽  
Soil Layer ◽  
Soil Samples ◽  
Pig Slurry ◽  
Soil Layers ◽  
Surface Soil Layer ◽  
N Requirement ◽  
Cu And Zn

Successive applications of pig slurry and pig deep litter may lead to an accumulation of copper (Cu) and zinc (Zn) fractions in the soil profile. The objective of this study was to evaluate the Cu and Zn forms and accumulation in a Sandy Typic Hapludalf soil after long-term application of pig slurry and deep litter. In March 2010, eight years after initiating an experiment in Braço do Norte, Santa Catarina (SC), Brazil, on a Sandy Typic Hapludalf soil, soil samples were collected from the 0-2.5, 2.5-5.0, 5-10 and 10-15 cm layers in treatments consisting of no manure application (control) and with applications of pig slurry and deep litter at two levels: the single and double rate of N requirement for maize and black oat succession. The soil was dried, ground in an agate mortar and analyzed for Cu and Zn contents by 0.01 mol L-1 EDTA and chemically fractionated to determine Cu and Zn. The applications of Pig deep litter and slurry at doses equivalent to 90 kg ha-1 N increased the contents of available Cu and Zn in the surface soil layer, if the double of this dose was applied in pig deep litter or double this dose in pig slurry, Cu and Zn migrated to a depth of 15 cm. Copper is accumulated mainly in the organic and residual fractions, and zinc preferentially in the fraction linked to clay minerals, especially in the surface soil layers.

Intra-soil milling for long-term efficient land use prospects 

2021 ◽  
Author(s):  
Saglara Mandzhieva ◽  
Vladimir Chernenko ◽  
Valery Kalinitchenko ◽  
Alexey Glinushkin ◽  
Alexey Zavalin ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Profile ◽  
Soil Layer ◽  
Illuvial Horizon ◽  
Fine Aggregate ◽  
Content Increase ◽  
Milling Machine ◽  
Processing Technologies

&lt;p&gt;Current land-use policy needs for innovative soil processing technologies. We carried out a long-term field experiment on the Kastanozem in following options: moldboard plowing to a depth of 22 cm; chiselling to a depth of 35 cm; three-tier PTN&amp;#8211;40 plowing to a depth of 40&amp;#8211;45 cm; PMS&amp;#8211;70 intra-soil milling of the 20&amp;#8211;45 cm layer. Moldboard, chisel and three-tier plowing does not improve soil aggregate system. 20&amp;#8211;45 cm soil layer milling by PMS&amp;#8211;70 provides the formation of the 1&amp;#8211;3 mm aggregates. 30&amp;#8211;40 years after PMS&amp;#8211;70 processing, the soil profile structure remained fine aggregate. Soil organic matter and dissolved organic matter content, as well as the soil productivity, were higher after PMS&amp;#8211;70. New intra-soil milling machine PMS&amp;#8211;260 was developed. The moldboard plowing did not change the natural soil profile vertical morphological differentiation. The soil loosening effect was short-term after soil chiselling. After the three-tier PTN-40 plowing, a large part of humus horizon material strews down the soil profile between the chaotically spread large structural blocks of illuvial and transitional horizons. After PMS&amp;#8211;70 processing, the content of 1&amp;#8211;3 mm size aggregate particle fraction in the illuvial horizon was triple compared to the three-tier PTN&amp;#8211;40 plowing. The soil desalination was intensive after PMS&amp;#8211;70. The absorbed Na&lt;sup&gt;+&lt;/sup&gt; content in solonetz was about 18&amp;#8211;20% of soil cation exchange capacity (CEC) in the moldboard option. The same was after the chiselling. The CEC Na&lt;sup&gt;+&lt;/sup&gt; content was of 14&amp;#8211;16% after the PTN&amp;#8211;40. The CEC Na&lt;sup&gt;+&lt;/sup&gt; content was of 10&amp;#8211;12% after the PMS&amp;#8211;70. The SOM content in the 0&amp;#173;&amp;#8211;20 cm soil layer was 2.0%, in the 20-40 cm layer of 1.3%; the DOM content was 0.03% and 0.02% respectively in moldboard plowing option. The SOM and DOM content increased slightly in a period 3&amp;#8211;4 years after chiselling. The SOM content was 2.2% in the 0&amp;#173;&amp;#8211;20 cm, and 1.4% in the 20&amp;#8211;40 cm; the DOM content was 0.04% and 0.03% respectively after the PTN&amp;#8211;40. The SOM content increased to 3.3% in the 0&amp;#8211;20 cm soil layer, and to 2.1% in the 20&amp;#8211;40 cm layer; the DOM content increase was 0.05% and 0.04% respectively after the PMS&amp;#8211;70. In the moldboard option, the rhizosphere developed only in the upper soil layer of 0&amp;#8211;20 cm. The rhizosphere spreads through the soil crevices after chilling. The conditions of rhizosphere development were better in the local comfort zones of the soil profile after three-tier PTN&amp;#8211;40 plowing. The rhizosphere developed well and uniformly both in the upper 0&amp;#8211;20 cm and in the 20-45 cm layer after intra-soil milling by PMS&amp;#8211;70. Improved plant growing conditions provide higher plant resistivity to pathogens. &amp;#160;The technology life cycle profitability: moldboard 21.5%, chiseling 6.9%, three-tier 15.6%, intra-soil milling 45.6%. The new design of intra-soil milling machine provides five times less traction resistance; 80% increased reliability, halving energy costs. Intra-soil milling provides long-term land-use prospects.&lt;/p&gt;&lt;p&gt;The research was supported by the RFBR, project no. 18-29-25071, and by the President of the Russian Federation, no. MK-2244.2020.5.&lt;/p&gt;

Effects of composted feedlot manure on the chemical characteristics of duplex soils in north-eastern Victoria

2002 ◽  
Vol 42 (3) ◽  
pp. 369 ◽  
Author(s):  
W. J. Slattery ◽  
B. Christy ◽  
B. M. Carmody ◽  
B. Gales
Keyword(s):  
Soil Profile ◽  
Agricultural Land ◽  
Agricultural Soils ◽  
Soil Layer ◽  
High Porosity ◽  
Long Term Effects ◽  
Nitrogen And Phosphorus ◽  
Beneficial Effects ◽  
North Eastern

The beef feedlot industry in Australia produces a large amount of solid organic by-product each year that is currently applied to agricultural land as a fertiliser supplement. Manure is known to be a valuable source of organic matter and some plant nutrients, especially nitrogen and phosphorus. In addition, manure contains excessive quantities of cations such as sodium (Na) and potassium (K), which may result in long-term sustainability problems for the soil, particularly when large amounts are applied over short time periods. The aim of this study was to determine the effects of composted beef feedlot manure when applied to agricultural soils. Two sites were selected, one a brown Dermosol and the other a red Kurosol, both in north-eastern Victoria near the Rutherglen Research Institute. Both sites received rates of manure up to 109 t/ha in 1996. In 1997 soil samples were collected and compared with untreated control soils. The Dermosol site was sown to an oat and clover mixture in 1996 and 1997 and the red Kurosol was sown to lupin in 1996 and wheat in 1997. The application of composted bovine manure resulted in a 1% increase in soil organic carbon, an increase in soil pH by 1.5 units, increased levels of magnesium, calcium, nitrogen and K in the surface 10 cm soil layer at both sites and an increase in extractable phosphorus levels in the subsoil. There was no detectable increase in surface Na, although there was a small but significant decrease in Na in the 40–80 cm soil layer. It is suggested that soluble organic compounds, migrating down through the soil profile are able to complex with Na and effectively remove some of this cation from the exchange sites of the clay surfaces. In addition, the high porosity of these soils coupled with the high degree of Na mobility ensures that most of this cation is transported deeper into the soil profile. The beneficial effects of applying composted manure are promising as a means of reducing sodicity although these results will require further validation. In addition, the long-term effects of saturating subsurface soil with Na are also a cause for concern and need to be further investigated.

scholarly journals Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 3. Soil Solution Chemistry

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 826
Author(s):  
Geoffrey C. Anderson ◽  
Shahab Pathan ◽  
David J. M. Hall ◽  
Rajesh Sharma ◽  
James Easton
Keyword(s):  
Ionic Strength ◽  
Soil Solution ◽  
Soil Profile ◽  
Soil Layer ◽  
Solution Chemistry ◽  
Soil Solution Chemistry ◽  
Short Term ◽  
Solution Ionic Strength ◽  
Gypsum Application

Aluminum (Al) toxicity imposes a significant limitation to crop production in South Western Australia. This paper examines the impact of surface-applied lime and gypsum on soil solution chemistry in the short term (1 year) and the long-term (10 years) in water limited environments. In the experiments, we measured soil solution chemistry using a paste extract on soil profile samples collected to a depth of 50 cm. We then used the chemical equilibrium model MINTEQ to predict the presence and relative concentrations of Al species that are toxic to root growth (Al associated with Al3+ and AlOH2 or Toxic-Al) and less non-toxic forms of Al bound with sulfate, other hydroxide species and organic matter. A feature of the soils used in the experiment is that they have a low capacity to adsorb sulfate. In the short term, despite the low amount of rainfall (279 mm), sulfate derived from the surface gypsum application is rapidly leached into the soil profile. There was no self-liming effect, as evidenced by there being no change in soil solution pH. The application of gypsum, in the short term, increased soil solution ionic strength by 524–681% in the 0–10 cm soil layer declining to 75–109% in the 30–40 cm soil layer due to an increase in soil solution sulfate and calcium concentrations. Calcium from the gypsum application displaces Al from the exchange sites to increase soil solution Al activity in the gypsum treatments by 155–233% in the short term and by 70–196% in the long term to a depth of 40 cm. However, there was no effect on Toxic-Al due to Al sulfate precipitation. In the long term, sulfate leaching from the soil profile results in a decline in soil solution ionic strength. Application of lime results in leaching of alkalinity into the soil profile leading to a decreased Toxic-Al to a depth of 30 cm in the long term, but it did not affect Toxic-Al in the short term. Combining an application of lime with gypsum had the same impact on soil solution properties as gypsum alone in the short term and as lime alone in the long term.

scholarly journals Intra-Soil Milling for Stable Evolution and High Productivity of Kastanozem Soil

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1302
Author(s):  
Valery Petrovich Kalinitchenko ◽  
Alexey Pavlovich Glinushkin ◽  
Vladimir Konstantinovich Sharshak ◽  
Evgene Panteleimonovich Ladan ◽  
Tatiana Mikhailovna Minkina ◽  
...  
Keyword(s):  
Soil Profile ◽  
Spring Barley ◽  
Soil Layer ◽  
Soil Bulk Density ◽  
Soil Salinization ◽  
Illuvial Horizon ◽  
High Productivity ◽  
Neutral Soil ◽  
Technology Life Cycle

The long-term field experiment on the Kastanozem showed that the standard moldboard plowing to a depth of 22 cm (control), chiseling to a depth of 35 cm, and three-tier plowing (machine type PTN–40) to a depth of 45 cm was incapable of providing a stable soil structure and aggregate system. The transcendental Biogeosystem Technique (BGT*) methodology for intra-soil milling of the 20–45 cm layer and the intra-soil milling PMS–70 machine were developed. The PMS–70 soil processing provided the content of 1–3 mm sized aggregate particle fraction in the illuvial horizon of about 50 to 60%, which was 3-fold higher compared to standard plowing systems. Soil bulk density reduced in the layer 20–40 cm to 1.35 t m−3 compared to 1.51 t m−3 in the control option. In the control, the rhizosphere developed only in the soil upper layer. There were 1.3 roots per cm−2 in 0–20 cm, and 0.2 roots per cm−2 in 20–40 cm. The rhizosphere spreads only through the soil crevices after chilling. After three-tier plowing (PTN–40), the rhizosphere developed better in the local comfort zones of the soil profile between soil blocks impermeable for roots. After intra-soil milling PMS–70, the rhizosphere developed uniformly in the whole soil profile: 2.2 roots per cm−2 in 0–20 cm; 1.7 roots per cm−2 in 20–40 cm. Matric water potential was higher, soil salinization was lower, and the pH was close to neutral. Soil organic matter (SOM) content increased to 3.3% in 0–20 cm and 2.1% in 20–40 cm compared to the control (2.0% in the 0–20 cm soil layer and 1.3% in the 20–40 cm layer). The spring barley yield was 53% higher compared to the control. The technology life cycle profitability was moldboard 21.5%, chiseling 6.9%, three-tier 15.6%, and intra-soil milling 45.6%. The new design of the intra-soil milling machine provides five times less traction resistance and 80% increased reliability, halving energy costs.

Long-term effects of liquid hog manure on the phosphorus status of a silt loam cropped to corn

2003 ◽  
Vol 83 (5) ◽  
pp. 589-600 ◽  
Author(s):  
I. Royer ◽  
R. R. Simard ◽  
G. M. Barnett ◽  
D. Cluis ◽  
D. A. Angers
Keyword(s):  
Water Contamination ◽  
Water Soluble ◽  
Silt Loam ◽  
Long Term Effects ◽  
Soil P ◽  
Total Soil ◽  
P Content ◽  
Hog Manure ◽  
Labile P

Repeated application of animal manure or mineral P fertilizer can significantly increase soil P content and enhance the risk of water contamination. The objectives of this study were to evaluate the long-term (8 yr) effect of liquid hog manure (LHM) applied at high rates and its timing of application on the soil P status and on the risk index of water contamination by P. Spring (S), fall (F), or spring + fall (SF) applications of LHM on a silt loam (Humo Ferric Podzol) were compared to recommended application rates of mineral fertilizer (MF) in a continuous corn (Zea mays L.) system. Total P applied ranged from 7 to 34 kg P ha-1 yr-1 in the MF treatment and from 106 to 150 kg P haP ha-1 yr-1 in the LHM treatments. Soil samples were collected to 1.0-m depth after one, six and eight annual applications. Applying high rates of LHM for 8 consecutive years resulted in a significant (P ≤ 0.10) enrichment in total soil P content relative to MF at the 0- to 20-cm soil depth. The effects of LHM on labile P forms (water soluble P, Pw and Mehlich-III extractable P, M3P) were also restricted to the 0- to 20-cm depth with values as high as 11 mg kg-1 for Pw and 241 mg kg-1 for M3P in the LHM plots. The degree of soil P saturation, evaluated as Pox/(Alox+Feox), increased to 15% in the 0- to 20-cm depth after 6 to 8 yr of LHM application. Saturation values of 12 to 15% were also found at the 80- to 100-cm depth in some LHM plots. The P index rating was always medium (109 to 216) in soil receiving MF but was high (217 to 432) after 6 to 8 yr of heavy LHM applications, which indicates a high potential risk of soil P transfer to surface water. The results of this study showed that timing of application had little influence on long-term soil P status. Overall, applying LHM at high rates greatly increased total soil P, the degree of soil P saturation, and the labile P forms in the surface horizons but had little effects below 20 cm. Key words: Hog manure, soil P, long-term effects, labile P, P saturation

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