Sorption of Phosphorus from Fertilizer Mixture

Studying phosphorus (P) sorption behavior is among the prerequisites for P management in the crop fields. The work presented in this chapter described P sorption data when fertilizer mixture (NH4NO3, KH2PO4, and KCl) was used to characterize sorption on soil. In addition to using fertilizer mixture, sorption experiments were also conducted using KH2PO4 prepared in 0.01 M KCl, 0.005 M CaCl2, and deionized water. The 24-h batch sorption experiments were conducted using a sandy soil to solution ratio of 1:2, and the equilibrium solution and sorbed data were described using Freundlich isotherm. Sorption kinetics experiments were conducted using times, 4, 8, 12, and 24 h. The Freundlich isotherm constant and sorbed P kinetics data for 0.005 M CaCl2 were significantly greater (p < 0.05) than for 0.01 M KCl and/or fertilizer mixture. The Freundlich isotherm constant and sorbed P kinetics data for deionized water were significantly lower (p < 0.05) than for 0.01 M KCl and/or fertilizer mixture. There was no significant difference in Freundlich isotherm constant and sorbed P kinetics data for 0.01 M KCl and fertilizer mixture. The sorption data showed the importance of using the fertilizer mix applied to the field when conducting sorption experiments

Adsorption-desorption of chlorpyrifos in soils and sediments from the Rufiji Delta, Tanzania

Batch adsorption-desorption equilibrium techniques were used to investigate the adsorption capacity and influence of salinity on partitioning of the insecticide chlorpyrifos between water and soil or water and sediments from the Rufiji Delta. The data were fitted to different adsorption-desorption models and the hysteresis index was calculated using the ratio between the Freundlich exponents for desorption and adsorption, and secondly, the difference in area under the normalized adsorption and desorption isotherms using the maximum adsorbed and solution concentrations. The data showed non-linear adsorption and that chlorpyrifos was strongly adsorbed to soil and sediments from the Rufiji Delta. The linearized adsorption coefficient (KD) and Freundlich adsorption coefficient (Kf) correlated significantly with organic carbon content. Chlorpyrifos adsorption as well as hysteresis calculated by both methods decreased with salinity (i.e. the sediment adsorbs increasing amounts of chlorpyrifos with decreasing salinity). This indicates that settling of freshwater sediments is among the major removal pathways of the chemical from the water column, but increased turbulence during high tides may resuspend settled sediment simultaneously increasing salinity and re-dissolve chlorpyrifos. However, discharge of fresh water, particularly during heavy rains, increases the trapping efficiency of the sediments. The theoretical approach developed showed that the Langmuir model describes the desorption data better than the Freundlich model, and that a better index of hysteresis is one that considers areas under the adsorption and desorption isotherms, provided the desorption isotherm is described by the normalized Langmuir isotherm and the adsorption isotherm by the normalized Freundlich isotherm

How Safe is Chicken Litter for Land Application as an Organic Fertilizer?: A Review

Chicken litter application on land as an organic fertilizer is the cheapest and most environmentally safe method of disposing of the volume generated from the rapidly expanding poultry industry worldwide. However, little is known about the safety of chicken litter for land application and general release into the environment. Bridging this knowledge gap is crucial for maximizing the benefits of chicken litter as an organic fertilizer and mitigating negative impacts on human and environmental health. The key safety concerns of chicken litter are its contamination with pathogens, including bacteria, fungi, helminthes, parasitic protozoa, and viruses; antibiotics and antibiotic-resistant genes; growth hormones such as egg and meat boosters; heavy metals; and pesticides. Despite the paucity of literature about chicken litter safety for land application, the existing information was scattered and disjointed in various sources, thus making them not easily accessible and difficult to interpret. We consolidated scattered pieces of information about known contaminants found in chicken litter that are of potential risk to human, animal, and environmental health and how they are spread. This review tested the hypothesis that in its current form, chicken litter does not meet the minimum standards for application as organic fertilizer. The review entails a meta-analysis of technical reports, conference proceedings, peer-reviewed journal articles, and internet texts. Our findings indicate that direct land application of chicken litter could be harming animal, human, and environmental health. For example, counts of pathogenic strains of Eschericia coli (105&ndash;1010 CFU g&minus;1) and Coliform bacteria (106&ndash;108 CFU g&minus;1) exceeded the maximum permissible limits (MPLs) for land application. In Australia, 100% of broiler litter tested was contaminated with Actinobacillus and re-used broiler litter was more contaminated with Salmonella than non-re-used broiler litter. Similarly, in the US, all (100%) broiler litter was contaminated with Eschericia coli containing genes resistant to over seven antibiotics, particularly amoxicillin, ceftiofur, tetracycline, and sulfonamide. Chicken litter is also contaminated with a vast array of antibiotics and heavy metals. There are no standards set specifically for chicken litter for most of its known contaminants. Even where standards exist for related products such as compost, there is wide variation across countries and bodies mandated to set standards for safe disposal of organic wastes. More rigorous studies are needed to ascertain the level of contamination in chicken litter from both broilers and layers, especially in developing countries where there is hardly any data; set standards for all the contaminants; and standardize these standards across all agencies, for safe disposal of chicken litter on land

Soil Fertility Assessment of Semiarid Soils from Nigeria Cropped to Sorghum

The aim of this study is to characterize the fertility status of the Dingyadi soils from semiarid Northern Nigeria, by using different methods of extraction to assess the potential for soil available macro and micronutrients to the sorghum crop. The study also compared concentrations of extractable nutrients between extractants for ascertaining the possibility of using one method to quantify a variety of plant-available nutrients in soils. Surface (0-15 cm) and sub-surface (15-30 cm) soil samples were collected along a topo-sequence at Dingyadi Sokoto-Nigeria, where sorghum had been grown, to characterize the soil chemical and physical properties that can influence soil fertility for sorghum production. The topo-sequence consisted of valley floor (TLL1), middle (TUP2), and crest (TUP3) positions of the slope. At each position 60 concentrations of each plant nutrient were used for the comparisons.Soil extraction for nutrients was carried out at the Environmental Soil Physics laboratory, Soil and Water Sciences Department, University of Florida, while analysis of aliquots for the elements was carried out at the Southwest Florida Research and Education Center, Immokalee, Florida. The study was carried out over a period of eight months, in 2016-2017. Soil samples were extracted using different extraction methods (Mehlich-3, Bray-1, Ammonium acetate, and DI-Water). A soil to solution ratio of 1:1 was used across all extraction methods to facilitate comparison between methods. However, a test was carried out to examine the effect of soil to solution ratio of (1:10) on extractable macro nutrients using Mehlich3 for randomly selected soil samples across the topo-sequence. Soil samples were also analyzed for texture, pH, organic matter, and cation exchange capacity (CEC). All soil soils were sandy, low in organic matter content, and CEC.With respect to sorghum production, the soils had adequate nutrients (Mg, Ca, K, and P) and soil pH. All soil samples contained no exchangeable K. Mehlich3 extracted higher available P than Bray1 in TLL1, but equal amounts in TUP2 and TUP3. Good correlations exist between extracting methods for macro nutrients (Mg, Ca, K, and P). Bray1 method used for available P is not suitable for soils that have pH greater than 7 determined in water. Mehlich3 is more suitable for the semiarid soils of Northern Nigeria that are acidic or alkaline. The Mehlich3 method should be calibrated with yield response of crops to substitute for Bray1 available phosphorus. Also, Mehlich3 method could be used for the multi-nutrient test with a good correlation with other methods like ammonium acetate for exchangeable bases

Imidacloprid soil movement under micro-sprinkler irrigation and soil-drench applications to control Asian citrus psyllid (ACP) and citrus leafminer (CLM).

Imidacloprid (IM) is used to control the Asian Citrus Psyllid (ACP) and citrus leafminer (CLM), which are related to the spread of huanglongbing (HLB or citrus greening) and citrus canker diseases, respectively. In Florida citrus, imidacloprid is mainly soil-drenched around the trees for proper root uptake and translocation into plant canopy to impact ACP and CLM. The objective of this study was to determine the effect of imidacloprid rate, and irrigate amount on concentration of imidacloprid in the soil following drench application to citrus trees in three age classes. The plots were established at the Southwest Florida Research and Education Center, Immokalee, using a randomized complete-block design for three age classes of trees: one-year-old trees (B1), three to five-year-old trees (B2), and eight-year-old trees (B3). The treatments were a combination of two rates each of imidacloprid (1D, 2D) and micro-sprinkling irrigation (1I, 2I). Imidacloprid and bromide (Br-) used as tracer were applied simultaneously. Soil moisture and concentrations of imidacloprid and Br were monitored using soil cores from hand held augers. Soil moisture content (θV) did not differ under two irrigation rates at any given observation day or depth, except following heavy rainfall events. Br- was lost from the observation depths (0-45 cm) about two weeks after soil-drench. Contrarily, imidacloprid persisted for a much longer time (4-8 weeks) at all soil depths, regardless of treatment combinations. The higher retardation of imidacloprid was related to the predominantly unsaturated conditions of the soil (which in turn reduced soil hydraulic conductivities by orders of magnitude), the imidacloprid sorption on soil organic matter, and the citrus root uptake. Findings of this study are important for citrus growers coping with the citrus greening and citrus canker diseases because they suggest that imidacloprid soil drenches can still be an effective control measure of ACP and CLM, and the potential for imidacloprid leaching to groundwater is minimal

THE ROLE OF HUMIC ACIDS FROM CARBONATIC SOILS IN THE SORPTION PROCESS OF AMETRYNE AND DIURON

Pesticide sorption in soil involves many factors, such as pH, soil redox, the amount and type of humic acids (organic matter), clays and metallic species. Little work in carbonatic soils has been done to study the effect of the above mentioned factors on the sorption of pesticides. Studies were conducted to determine the interaction between these factors and the carbonatic soils. Twelve carbonatic soil series and nine non-carbonatic soil series showed that redox properties for carbonatic soils tended to be smaller and, contrary to the non-carbonatic soils, many of them with negative potentials. We observed a positive correlation between water extractable iron versus diluted acid extractable iron for the carbonatic soils (R2 = 0.88) but not for the non-carbonatic soils. This finding suggests that the reductive environment of carbonatic soils favors the ferrous species (Fe+2) rather than the ferric (Fe+3). These factors apparently affect the solubility of the organic matter, thus decreasing the sorption of pesticides in carbonatic soils compared to that of non-carbonatic. We observed a positive correlation between the extinction coefficients (k) at 280 nm for the humic acids of carbonatic soils and the sorption coefficients of atrazine and diuron (R2 = 0.61 and 0.56, respectively). The k values at 300 nm did not show a significant correlation. The averaged pKa values for humic acids from the soils in this study were similar. However, the first derivative titration plots of humic acids showed that humic acids from soils in this study contained several kinds of functional groups with different pKa values, and also suggest that the properties of the functional groups are different. The data suggest that the aromatic rather than the aliphatic content of humic acids seems to have a predominant role in the soil sorption of pesticides. These findings indicate the importance of studying more in depth the sorption, mobility and degradation of pesticides in carbonatic soils in order to protect the water resources