Charles L. Mulchi’s research while affiliated with University of Maryland, College Park and other places

The objective of this research was to assess the long-term effects of broiler litter applications on soil phosphorus (P), copper (Cu), zinc (Zn), manganese (Mn), and arsenic (As) concentrations in Chesapeake Bay watershed Coastal Plain soils. Litter and soil samples were collected from 10 farms with more than 40 years of broiler production and from wooded sites adjacent to fields and were analyzed for P and metal contents. Averaged over farms, total P and metal concentrations in the litter were 12.8 g kg-1 P and 332, 350, 334, and 2.93 mg kg-1 Cu, Zn, Mn, and As, respectively. Surface (0-15 cm) soil pH values were greater than (5.7-6.4) the 0- to 15-cm depth at wooded sites (3.5-4.3). Surface soil Bray 1 P values (149-796 mg kg-1) in amended fields were greater than wooded sites (4.4-17 mg kg-1). The 1N nitric acid (HNO3)-extractable metal concentrations were higher in amended soils than in wooded areas and were 7.7-32, 5.7-26, 12.3-71, and 0.6-3.0 mg kg-1 for Cu, Zn, Mn, and As, respectively, compared to 0.76-14, 4.6-22, 1.6-70, and 0.14-0.59 mg kg-1 for the same metals, respectively, in wooded areas. Results from this study demonstrated that long-term broiler litter applications have altered the chemical properties of the Coastal Plain soils of the Maryland Eastern Shore. Metal concentrations were low in the surface layer of amended fields and typically decreased with depth. Phosphorus additions rather than metals are most likely to contribute to the degradation of the Chesapeake Bay watershed.

The potential for phosphorus (P) movement from poultry-litter amended soils into surface waters heightens the need to manage elevated P concentrations. Amending high P soils with aluminum (Al) rich drinking water treatment residue in a greenhouse study reduced water extractable P levels and induced P deficiency in container grown wheat. Objectives of the current investigation were to determine the effect of water treatment residue on grain yield, leaf and grain mineral nutrient concentrations in corn (Zea mays L.) grown under field conditions and to examine pH, water and Mehlich 3-extractable P, and 0.01 M calcium chloride extractable Al in the amended soils at two sites. Poultry litter was amended with 0, 5.6, and 11.2 Mg ha(-1) of water treatment residual and applied to two sites prior to planting with corn in 1998. Additional rates (16.8 and 33.6 Mg ha(-1)) of water treatment residue were applied directly to half of each plot on site I in 1999. Results indicated that water treatment residue application did not adversely affect corn grain yields or alter concentrations of mineral nutrients in leaves and grain. Water and Mehlich 3-extractable P and calcium chloride extractable Al concentrations were unchanged with water treatment residue applications in both years on both sites. Further studies are needed concerning optimal annual dosages and long term loading rates for direct soil application of water treatment residue to reduce soluble phosphorus.

Use of aluminum (Al)-rich compounds to reduce the solubility of phosphorus (P) in poultry litter and litter amended soils is being used as a method to inactivate (precipitate or adsorb) P in high P soils. Previous studies have shown that Drinking Water Treatment Residue (DWTR) rich in Al significantly lowered soluble P in litter amended soils; however, this could result in P deficiency in crops. A growth chamber experiment was conducted using Matapeake, Evesboro, and Woodstown soils containing Mehlich 3 extractable P levels above 800 mg kg−1 in order to 1) determine the effects of DWTR soil treatment on plant dry biomass yield (BM), P and manganese (Mn) uptake; and 2) examine pH, extractable P, Mn, and Al concentrations in soils after three cropping cycles with wheat. DWTR was mixed with the soils at rates equal to 0, 10, 25, and 50 g kg−1 soil, followed by incubation for seven weeks. Three cycles of wheat (Triticum aestivum) were grown in succession. DWTR application significantly reduced plant dry matter yields for Evesboro and Woodstown soils at rates above 10 g kg−1 DWTR, but not in Matapeake. Plant P concentration progressively reduced with increased rates of DWTR during the three cropping cycles for the three soils. Plant tissue P concentrations appeared above sufficiency levels for wheat for all three soils at 10 g kg−1 rate of DWTR during the first cropping cycle. At the 25 and 50 g kg−1 rates, however, tissue P concentrations were either low or deficient for the second and third cycle. Both water soluble and Mehlich 3 extractable P exhibited reductions with increased DWTR application rates and cropping cycle. Significant correlations were found between water soluble, Mehlich 3 extractable P and plant P concentrations for all the soils; however, the r2 values were generally higher for water soluble P compared to the Mehlich 3 extractable P. Soil pH values typically increased with DWTR application rate, but extractable Al concentrations, measured after each cropping cycle, remained below 2 mg kg−1 for both the treated and untreated soils. DWTR was capable of reducing water soluble phosphate in these soils without severely impacting soil fertility.

Glycine max (L.) Merr. was grown under several light conditions to determine the role of red and far-red radiation in plant adaptation to vegetation shade. Neutral density,‘neutral’ density with elevated far-red radiation, and green shade treatments were used in a greenhouse, producing calculated phytochrome photostationary state (Pfr/Pr+Pfr) values of 0.68, 0.63 and 0.51, respectively. Cool-white fluorescent lamps either alone or in conjunction with far-red fluorescent lamps were used in a growth chamber, providing Pfr/Pr+Pfr of 0.79 and 0.61, respectively. Daily photo-synthetically active radiation was about 25% of daylight and was approximately equal for both greenhouse (2.15MJ m−2) and growth chamber (2.57MJ m−2). Developmental stage 4 weeks after sowing was similar for all treatments, but axillary growth and rates of leaf area and dry matter accretion differed between plants from greenhouse and growth chamber. Light conditions simulating vegetation shade (i.e. a low ratio of red to far-red radiation) significantly promoted petiole elongation and retarded the rate of stem elongation in both greenhouse and growth chamber experiments. Other aspects of growth either were not significantly altered by spectral quality or were not modified consistently in both greenhouse and growth chamber environments. Net photosynthetic rates measured under growth conditions for unifoliate and first trifoliolate (TF1) leaves of growth chamber plants between 9 and 21 d after sowing were generally unaffected by spectral quality, but supplemental FR enhanced TF1 leaf area expansion. The latter effect was not correlated with increased dry matter accumulation. The significance of spectral quality for adaptation of soybeans to canopy closure and intercropping is discussed.

Leaf and canopy fluorescence properties of field corn (Zea mays L.) grown under varying levels of nitrogen (N) fertilization were characterized to provide an improved N sensing capability which may assist growers in site-specific N management decisions. In vivo fluorescence emissions can occur in the wavelength region from 300 to 800 nm and are dependent on the wavelength of illumination. These light emissions have been grouped into five primary bands with maxima most frequently received from corn at 320 nm (UV), 450 nm (blue), 530 nm (green), 685 nm (red), and 740 nm (far-red). Two active fluorescence sensing systems have been custom developed; a leaf level Fluorescence Imaging System (FIS), and a canopy level Laser Induced Fluorescence Imaging System (LIFIS). FIS sequentially acquires high-resolution images of fluorescence emission bands under darkened laboratory conditions, while LIFIS simultaneously acquires four band images of plant canopies >or= 1 m2 under ambient sunlit conditions. Fluorescence emissions induced by these systems along with additional biophysical measures of crop condition; namely, chlorophyll content, N/C ratio, leaf area index (LAI), and grain yield, exhibited similar curvilinear responses to levels of supplied N. A number of significant linear correlations were found among band emissions and several band ratios versus measures of crop condition. Significant differences were obtained for several fluorescence band ratios with respect to the level of supplied N. Leaf adaxial versus abaxial surface emissions exhibited opposing trends with respect to the level of supplied N. Evidence supports that this confounding effect could be removed in part by the green/blue and green/red ratio images. The FIS and LIFIS active fluorescence sensor systems yielded results which support the underlying hypothesis that leaf and canopy fluorescence emissions are associated with other biophysical attributes of crop growth and this information could potentially assist in the site-specific management of variable-rate N fertilization programs.

Open-top chambers (OTC`s) were conducted to determine interactive effects of atmospheric CO₂ and O₃ air pollution on photosynthetic responses in wheat. The plants were grown full-season in these chambers supplied with charcoal-filtered air (CF) as control, CF + 155 μ L CO₂ L ^-1 as high CO₂, non-filtered air (NF) + 40nL O₃ L ^-1 as high O₃ and NF + 155 μ L CO₂ L ^-1 + 40nL O₃ L ^-1 as combined high CO₂ and high O₃. Photosynthetic rates (P_n) were measured three times during vegetative and reproductive stages with portable gas exchange system (LI-COR 6200). In general, P_n rates were stimulated by high CO₂ and reduced by high O₃ but in some cases, combined high CO₂ and high O₃ increased the P_n rates. The data showed continuous increases in P_n rates during pre-flowering and early seed formation and drops during late seed formation stage. This study supports that the concentration of CO₂ at 5 ± 500 μ L L ^-1 treatment had a protective role against adverse impacts of O₃ exposure at concentration 5 ± 60nL L ^-1 treatments.

Reducing the environmental risk from soluble phosphorus (P) in long-term poultry manured fields can involve increased use of chemical soil amendments such as aluminum (Al), calcium (Ca), and iron (Fe). Iron salts have been proven effective in removing soluble P from wastewater and have been used to inactivate P in poultry litter and litter-amended soils. The potential for P deficiency in crops grown on Fe treated soils is of concern. A growth chamber experiment was conducted using Matapeake, Evesboro, and Woodstown soils with Mehlich 3 extractable P (M3-P) levels above 800 mg kg in order to 1) determine the effects of a Fe-rich residue (IRR) on crop biomass yield and on plant P, Mn, and Fe contents, and 2) examine pH, electrical conductivity (EC), P, Mn, and Fe concentrations in soils after three cropping cycles with wheat. IRR was mixed with the soils at rates of 0, 10, 25, and 50 g kg and incubated for seven weeks. Three crops of wheat (Triticum aestivum) were grown in succession. Biomass yield (BM) and tissue P concentrations were significantly reduced with the additions of IRR for all three soils, but the differences were much less at the 10 g kg application rate than at the 25 and 50 g kg rates. Biomass yield was 29% lower than the control at the 10 g kg IRR rate compared to 74% lower at the 50 g kg rate. Even though tissue P concentrations were reduced, levels were within the range considered sufficient for wheat growth for all treatments. The high Mn and DTPA-Fe in the IRR treatments increased tissue Mn and Fe concentrations, but the levels were below the concentration considered to be toxic to most crops. Water soluble P and M3-P concentrations were lowered with increased IRR application rate for each soil and correlated positively with tissue P for the three soils. DTPA extractable Mn concentrations in soil increased, but Fe concentrations decreased with increased IRR application, for the three soils. IRR treatments initially increased both pH and EC in the three soils, however, reductions in pH and EC values were found with subsequent cropping cycles. Further studies to identify and limit the negative impact of IRR on plant growth are needed before the materials should be considered for field application to sequester soluble P in high P soils.

The high phosphorus (P) soils in the poultry producing areas of Maryland's Eastern Shore pose an environmental risk to surface and ground water. Amendments with calcium (Ca) salts and calcium-rich byproducts have been considered in management practices for reducing P solubility in soil solution. A growth chamber experiment was conducted using fluidized bed coal ash (BA) at increasing rates on Matapeake, Evesboro, and Woodstown soils that had received poultry litter for over 30 years which increased Mehlich 3-phosphorus (M3-P) to levels above 800 mg kg. The objectives of the study were to 1) determine the effects of BA on plant dry biomass yield (BM), wheat tissue P and Mn levels, and 2) examine pH, extractable P and Mn concentrations in the BA treated soils following three cropping cycles. BA was incorporated into each soil at rates of 0, 10, 25, and 50 g kg soil followed by incubation for seven weeks. Three crops of “Grandin” wheat (Triticum aestivum L.) were grown in succession. Biomass yield (BM) was significantly reduced with BA additions for the three soils. Plant P concentrations were progressively lowered with increased rates of BA for all BA additions for all three soils. Plant Mn levels were substantially reduced with additions of BA in response to the large increase in pH for all soils. Soil pH values increased from 5.0±0.2 in the control soils to >10.2 at the 50 g kg rate, and decreased during cropping cycles. Both water soluble P (WSP) and M3-P concentrations were significantly decreased upon addition of BA in all soils. Although WSP concentrations showed higher correlations with plant P concentration than M3-P levels, in terms of P sequestration in soils, WSP amounts were reduced by an average of 27 mg kg and 33 mg kg at addition of 10 g kg and 50 g kg while M3-P quantities were reduced by approximately 130 mg kg and 500 mg kg, respectively, when averaged over soil and cycles. The large increase in soil pH, which reduced P in wheat at the 10 g kg BA, would suggest that this material may not be suitable for field application to sequester P in high P soils.

Early recognition of environmental stress factors that may ultimately result in the loss of productivity is essential for economical assessments of agricultural and forestry practices (Moran et al. 1997). Vast resources and management approaches are implemented to increase plant productivity. Rapid noninvasive assessment methods that can detect deleterious environmental effects on crops during early stages of growth in a timely manner would be of great value. A relatively new active sensing technique available for vegetative monitoring is steady-state fluorescence.