Irenus A. Tazisong

Tillage, cropping systems, and nitrogen fertilizer source effects on soil carbon sequestration and fractions.

Quantification of soil carbon (C) cycling as influenced by management practices is needed for C sequestration and soil quality improvement. We evaluated the 10-yr effects of tillage, cropping system, and N source on crop residue and soil C fractions at 0- to 20-cm depth in Decatur silt loam (clayey, kaolinitic, thermic, Typic Paleudults) in northern Alabama, USA. Treatments were incomplete factorial combinations of three tillage practices (no-till [NT], mulch till [MT], and conventional till [CT]), two cropping systems (cotton [Gossypium hirsutum L.]-cotton-corn [Zea mays L.] and rye [Secale cereale L.]/cotton-rye/cotton-corn), and two N fertilization sources and rates (0 and 100 kg N ha(-1) from NH(4)NO(3) and 100 and 200 kg N ha(-1) from poultry litter). Carbon fractions were soil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), and potential C mineralization (PCM). Crop residue varied among treatments and years and total residue from 1997 to 2005 was greater in rye/cotton-rye/cotton-corn than in cotton-cotton-corn and greater with NH(4)NO(3) than with poultry litter at 100 kg N ha(-1). The SOC content at 0 to 20 cm after 10 yr was greater with poultry litter than with NH(4)NO(3) in NT and CT, resulting in a C sequestration rate of 510 kg C ha(-1) yr(-1) with poultry litter compared with -120 to 147 kg C ha(-1) yr(-1) with NH(4)NO(3). Poultry litter also increased PCM and MBC compared with NH(4)NO(3). Cropping increased SOC, POC, and PCM compared with fallow in NT. Long-term poultry litter application or continuous cropping increased soil C storage and microbial biomass and activity compared with inorganic N fertilization or fallow, indicating that these management practices can sequester C, offset atmospheric CO(2) levels, and improve soil and environmental quality.

Influence of Tillage, Cropping, and Nitrogen Source on the Chemical Characteristics of Humic Acid, Fulvic Acid, and Water-Soluble Soil Organic Matter Fractions of a Long-Term Cropping System Study

The characterization of organic matter in agroecosystems is important because of its involvement in many important soil ecosystem processes. Humic acid, fulvic acid, and water-extractable organic matter from a 9-year agroecosystem study investigating the effects of tillage, cropping system, and N source was characterized using multidimensional fluorescence spectroscopy with parallel factor analysis (PARAFAC). The fluorescence spectra suite containing all three types of organic matter fractions was modeled by five PARAFAC components. The distribution of component concentrations was unique to each type of organic matter fraction, indicating that these operational extracted fractions reflect differing chemical pools of soil organic matter. The three treatment factors (tillage, cropping, and N source) investigated in this study did not affect the component distribution of the humic and fulvic acid fractions that are regarded as the refractory pools of soil organic matter. In contrast, the component distribution of the more labile water-extractable organic matter fraction was significantly affected by the N source treatment. The results of this study support the use of multidimensional fluorescence spectroscopy with PARAFAC as a method to investigate how management practices of agroecosystems affect the dynamics and chemical nature of soil organic matter pools.

Nitrogen and Phosphorus Accumulation in Pasture Soil from Repeated Poultry Litter Application

Poultry litter (PL) is a traditionally inexpensive and effective fertilizer to improve soil quality and agricultural productivity. However, over application to soil has raised concern because excess nutrients in runoff could accelerate the eutrophication of fresh water. In this work, we determined the contents of total phosphorus (P), Mehlich 3 extracted P, total nitrogen (N), ammonium (NH4)‐N, and nitrate (NO3)‐N, in pasture soils receiving annual poultry litter applications of 0, 2.27, 2.27, 3.63, and 1.36 Mg/ha/ yr, respectively, for 0, 5, 10, 15, and 20 years. Samples were collected from three soil depths (0–20, 20–40, and 40–60 cm) of the Hartsells series (fine‐loamy, siliceous, subactive, thermic, Typic Hapludults) on a 3–8% slope in the Sand Mountain region of north Alabama. PL application increased levels of total P, Mehlich‐3 extractable P, and total N significantly. However, the change in NH4‐N and NO3‐N contents by the PL application was not statistically significant. Correlation analysis indicated that the contents of total P, Mehlich 3 extracted P, and total N were more related to cumulative amounts of poultry litter applied than the years of application or annual application rates alone. This observation suggested that N and P from poultry litter accumulated in soil. Predicting the build‐up based on the cumulative amounts of PL application, rather than isolated factors (i.e., application year or rate), would improve the accuracy of evaluating long‐term impacts of poultry litter application on soil nutrient levels.

Concentration and distribution of iron and manganese fractions in Alabama Ultisols

Information on metal forms and contributions of soil properties on metal distribution in Alabama soils is either limited or meager. This study chemically partitioned and evaluated soil Fe and Mn distributions and applied stepwise multiple regressions to identify the soil properties influencing their distributions in some Alabama Ultisols. Iron and Mn distributions among metal fractions were generally dependent on total metal content, soil properties, and degree of chemical weathering. Distributions among metal fractions showed that Fe was mainly in the residual fraction (> 85%), whereas Mn was predominantly oxide-bound and in the residual fraction (> 90%). The proportion of Fe fractions in the soils was in the order: residual > oxides (crystalline FeO, amorphous FeO, MnO) > organic > exchangeable, whereas Mn was in the order: oxide-bound (MnO, amorphous FeO, crystalline FeO,) > residual > exchangeable > organic fraction. Stepwise multiple regression analysis showed that pH accounted for 33% of the total variability in exchangeable Fe, whereas SOM accounted for 47.1% of the total variability in exchangeable Mn. Clay and sand contents accounted for 42.2 and 52.3%, respectively, of the total variability in the residual Fe fraction, whereas silt accounted for 19.7% of the total variability in residual Mn distribution in these soils.

Amino Compounds in Poultry Litter, Litter-Amended Pasture Soils and Grass Shoots

Amino compounds (ACs), i.e., amino acids and amino sugars, are the major forms of organic nitrogen (N) in animal manure and soil. To increase our understanding on the effect of long-term poultry litter (PL) application on soil AC pools and turnover, in this study, we determined the contents of 21 ACs in 23 PL samples, 15 soil samples collected from 0–20, 20–40, and 40–60 cm layers of five pasture plots with 0, 5, 10, 15 and 20 years of PL applications, and 5 grass shoot samples grown on these pasture fields. The contents of 21 ACs were simultaneously determined by methanesulfonic acid hydrolysis/extraction and anion chromatography-pulsed amperometry. PL application increased soil total and individual AC contents with a distribution pattern similar to that of AC in PL. The highest AC-N concentrations were observed in the soils with 10- or 15-year PL applications, inconsistent with the order of annual application rates or cumulative applied PL amounts. Application of PL increased the AC contents in grass shoots whereby the highest increase of most ACs was with the shoots from the fields that received PL for 5 years. These observations suggested that both freshly applied and residual PL had contributions to the soil AC-N, and that PL application also accelerated AC-N transformation in soil.

Inorganic and Enzymatically Hydrolyzable Organic Phosphorus of Alabama Decatur Silt Loam Soils Cropped With Upland Cotton

Abstract Alabama is a major cotton production state in the USA. In this study, we assessed the impact of soil management practices on phosphorus (P) forms and lability in Alabama Decatur silt loam cropped with cotton. The data indicated that inorganic P in the soils studied was mainly associated with Fe and Al oxides and was not readily bioavailable. On the other hand, elevated levels of water plus Fe and Al inorganic P fractions were observed in soils treated with poultry litter compared to the control and other inorganic fertilized soils. Most of the soil organic P was associated with Al oxide (> 40%) with the exception of the no-till and control treatments where the bulk of the soil organic P was organic matter bound. Water soluble organic P increased after poultry litter applications whereas no increase was observed with inorganic fertilization. Statistical analysis (mean separation) revealed that the phosphatase and phytase hydrolyzed water soluble organic P within each treatment was not significantly different at P < 0.05. More than 50% of organic P in the sequentially-extracted NaOH fraction was hydrolyzable by the various phosphatase enzymes, indicating that NaOH-extractable organic P is labile. Any portion of the organic P extracted in the fractions that was not hydrolyzed by the enzymes is considered to be in the complex forms tightly bound to colloidal and other materials.

Soil Properties and Macro Cations Status impacted by Long‐Term Applied Poultry Litter

Abstract Most ethnic populations worldwide consume poultry products. Whereas poultry litter (PL) is a traditionally inexpensive and effective fertilizer to improve soil quality and agricultural productivity, overapplication to soils has raised concerns because excess nutrients in runoff could accelerate the eutrophication of fresh bodies of water. A long‐term field experiment of land application of PL to soils used for pasture growth has been maintained for nearly two decades in the Sand Mountain region of north Alabama, USA. In this work, several soil parameters impacted by the long‐term applied litter were characterized. The findings clearly support previous general observations that long‐term applied litter on pasture soils altered soil properties and macrocation levels. Unlike other studies, however, the effects of applied litter at multiple rates and years were examined, thus revealing the dynamic impacts on soil properties. Hay yields increased with the increase of years of PL application, regardless of the applied rate. This observation was consistent with previous observations that the labile phosphorus (P) portion in these soils increases with application years whereas total P increases with the cumulative applied PL amounts. Poultry litter application did not markedly affect soil electric conductivity, bulk density, or sodium (Na) or potassium (K) levels, especially at the soil surface (0–20 cm). Soil pH, carbon (C), C/nitrogen (N) ratio, calcium (Ca), and magnesium (Mg) were profoundly affected at all three soil depths (0–20, 20–40, and 40–60 cm). Most soil parameters analyzed in this study reached peak values with 10–15 years of applied litter. This observation suggests that there was a turning point of impact for applied litter around 10 years: prior to that the soil macrocations were altered positively as a result of accumulative functions. Continuous litter application may negatively alter a soils capacity to retain macrocations, leading to less impact observed in this study. In other words, pasture soils with more than 10 years of applied litter would have higher potential for leaching and runoff. Our observation suggested that best management practices for land application of PL should take into consideration the different effects of PL application history.

Metal Contents in Soils of Alabama

Abstract Metal contamination of soils and water resources continues to be a serious public concern. Accumulations in the ecosystems and subsequent uptake by humans via the food chain pose a major health risk. The total copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn), cadmium (Cd), chromium (Cr), and lead (Pb) contents of eight benchmark soils of north Alabama were determined. The overall goal was to provide information for future pedological studies. The specific objectives were to determine baseline values of total Cu, Fe, Mn, Ni, and Zn, which are plant nutrients, and Cd, Cr, and Pb, which are relatively serious pollutants. Expressed in mg kg−1 soil, the ranges, median, geometric mean, and arithmetic mean values, respectively in parentheses, were Cu (3.2–81.9, 24, 18.2, 24.8); Cd (< 0.2–2.85, 0.15, < 0.1, 0.40); Cr (13.4–132, 51.7, 54.6, 61); Fe (1535–70,840, 34,035, 26,783, 31,720); Mn (30.2–4643, 540, 426, 1012); Ni (7.6–61, 27.5, 25.3, 27.7); Pb (< 2.0–22.8, < 2.0, < 0.1, 3.63); and Zn (22.6–339, 116, 108, 125). The order of abundance in the soils was Fe > Mn > Zn > Cr > Ni > Cu > Pb > Cd. Total Pb, Cd, Zn, Cu, and Ni contents determined were comparable to the reported average values for most United States soils. The presence of Cd, Cr, and Pb in measurable amounts in some of the samples is of environmental concern.

Long-Term Dynamics of Labile and Stable Phosphorus Following Poultry Litter Application to Pasture Soils

A major source of runoff phosphorus (P) from agricultural soils is land-applied animal manure. Our work reports P levels in pasture soils in northern Alabama affected by long-term (0–20 years) application of poultry litter (PL). Sequential fractionation revealed different buildup patterns of labile and stable P fractions in these soils. Phosphorus built up in subsurface (20–40 cm and 40–60 cm deep) soils with lower application rates than P accumulated in surface (0–20 cm deep) soils, indicating a greater potential for surface runoff than leaching from these pasture fields. Correlation analysis of the surface soils showed levels of stable P extractable by sodium hydroxide (NaOH) were related to the cumulative amount of PL applied. The level of water-extractable P increased because PL application was significantly related to the number of years the soil receiving PL, not the annual application rate or the cumulative amount of PL applied.

Phosphorus Forms and Mineralization Potentials of Alabama Upland Cotton Production Soils Amended with Poultry Litter

The essential role of phosphorus (P) in almost all biological processes has led to its extensive studies. Phosphorus in its inorganic form (Pi) is required for metabolic reactions and energy transfer. In contrast, organic P (Po) forms become bioavailable usually after hydrolysis to Pi. Organic P dephosphorylation in the soil environment is largely dependent on the stereochemical and stereoisomeric structures of the compounds in question. In addition, Po dephosphorylation also depends on the types and enzymes sources involved in such catalytic activities. This chapter focuses on P fractions and mineralization potentials of different P forms in poultry litter amended soils of northern Alabama cropped with cotton. Phosphorus forms characterized by solution 31P nuclear magnetic resonance (NMR) spectroscopy showed orthophosphate to be the dominant form, accounting for 63.6–76.1 % of the total P forms in these soils. A sequential fractionation was used to separate soil Pi and Po into several fractions. The fractionation revealed that soil Pi was mainly associated with Fe and Al oxides and was not readily bioavailable. Water-, Fe- and Al- associated Pi increased in soils treated with poultry litter compared with the control. The Ca-Al bound Po was the most abundant fraction with more than 40 % of the total Po but the Ca-Al bound Po values was lower for the control and no-tilled soils. Phosphatase enzymes were able to hydrolyze 7–62 % water, 17–53 % Ca-EDTA, 18–88 % Na-EDTA, 40–77 % H2SO4, and 50–75 % NaOH extractable Po. Information obtained from this study indicates that P dynamics and uptake in cotton soils amended with poultry litter is not well understood. More research is needed to better understand the impact of poultry litter application on P forms and mineralization potentials in cotton production soils.