Effects of Fertilizer Source and Rate on Zinnia Cut Flower Production in a High Tunnel

Sustainable nutrient management in high tunnel production is critical for optimizing crop yield and quality and improving soil health. In this study, we investigated the influence of different pre-plant composts (composted broiler litter, vemicompost, and cotton gin compost) in combination with different rates of organic or conventional fertilizer on zinnia plant growth, marketable yield of cut flower stems (>30 cm), and soil nutrients in a high tunnel over two years. Results showed that in general, pre-plant compost influenced plant growth, and plants that received composted broiler litter had the highest plant growth index. However, pre-plant compost did not affect the number of marketable cut stems. Fertigation during the growing season influenced the number of marketable cut stems. Comparable rates of nitrogen, from either organic or conventional fertilizer, produced similar numbers of marketable stems, suggesting that the organic fertilizer used in this study can be used as a fertilizer source for the production of zinnia cut flowers. After two years of production under the high tunnel, soil-extractable phosphorus, sodium, zinc, and pH significantly increased, suggesting that salt accumulation should be closely monitored in response to different compost or fertilizer sources with long-term production under high tunnels.

Does Soybean Yield and Seed Nutrient Content Change Due to Broiler Litter Application?

Broiler litter (BL) has the potential to be used as an alternative multi-nutrient source for soybean (Glycine max L.) production. While previous research on soybean yield response to BL has reported inconsistent results, the effects of BL application on soybean seed nutrient concentrations are largely unknown or less studied. The objective of this two-year field study was to investigate the effect of BL application on soybean yield and seed nutrient content in three different soil types and production environments. To pursue the objective, a field experiment was established in 2018 in a Compass loamy sand with four BL rates (0, 2.2, 5.6, and 11.2 Mg BL ha−1). In 2019, the study was expanded to include two additional soil types (Decatur silty clay loam and Dothan fine sandy loam) totaling four site years. The experimental design at each site was a randomized complete block with four replications. Application of BL had no impact on soybean yield in the first year, regardless of application rate and soil type. In the second year of BL application, soybean yield was 43% higher overall compared to no BL plots on a Compass loamy sand. However, soybean yield with the application of 5.6 or 11.2 Mg BL ha−1 was not statistically different from that at 2.2 Mg BL ha−1. Soybean seed Ca and B concentrations changed significantly among the treatments; however, the change was not consistent across the sites. Consecutive year application of 11.2 Mg BL ha−1 yr−1 produced the highest seed K and Cu concentrations. The results of this research suggest that repeated BL application can boost soybean yield and potentially enrich seed with selected nutrients.

Manure Source and Cropping System Affect Nutrient Uptake by Cactus (Nopalea cochenillifera Salm Dyck)

Forage cactus responds positively to organic fertilization. However, little is known about the mineralization dynamics of the various sources of existing organic fertilizers. Thus, the objective was to evaluate the release of nutrients from different manure types and the nutrient accumulation in forage cactus across different cropping systems. Different manure sources (cattle, goat, sheep, and broiler litter) were evaluated for the following cropping systems: (i) Gliricidia sepium intercropped with cactus cv. IPA-Sertânia; (ii) Leucaena leucocephala intercropped with cactus cv. IPA-Sertânia; and (iii) Cactus cv. IPA-Sertânia in monoculture, in the tropical semiarid region of Brazil. The rate of decomposition and release of N, P, and K from manure was determined by incubating a litterbag, evaluated in different periods (0, 4, 8, 16, 32, 64, 128, and 256 days). Broiler litter released the greatest amount of N and P. Sheep manure released the greatest amounts of K. The greatest accumulations of N, P, and K in cactus biomass occurred when broiler litter was applied. Cactus monoculture accumulated less N over 256 days, indicating that the presence of tree legumes favors the accumulation of N in cactus. Broiler litter promoted the best synchronism between N release and N uptake in different cropping systems.

Association of Broiler Litter Microbiome Composition and Campylobacter Isolation

Infection with Campylobacter species is one of the leading causes of bacterial diarrhea in humans in the US. Chickens, which become colonized on the farm, are important reservoirs of this bacterium. Campylobacter can establish itself in the broiler house via a variety of sources, can survive in the litter of the house, and possibly persist over successive flock cycles. However, the role of the broiler litter microbiome on Campylobacter persistence is not clear. A matched case-control study was conducted to determine whether the broiler litter microbiome composition was associated with Campylobacter isolation within the broiler house. Flocks were classified as cases when either Campylobacter jejuni or Campylobacter coli was isolated in boot sock samples, or as controls otherwise. Case and control flocks were matched at the broiler house level. Composite broiler litter samples were collected and used for DNA extraction and 16S rRNA gene V4 region sequencing. Reads were processed using the DADA2 pipeline to obtain a table of amplicon sequence variants. Alpha diversity and differential bacterial relative abundance were used as predictors of Campylobacter isolation status in conditional logistic regression models adjusting for flock age and sampling season. Beta diversity distances were used as regressors in stratified PERMANOVA with Campylobacter isolation status as predictor, and broiler house as stratum. When Campylobacter was isolated in boot socks, broiler litter microbiome richness and evenness were lower and higher, respectively, without reaching statistical significance. Campylobacter isolation status significantly explained a small proportion of the beta diversity (genus-level Aitchison dissimilarity distance). Clostridium and Anaerostipes were positively associated with Campylobacter isolation status, whereas Bifidobacterium, Anaerosporobacter, and Stenotrophomonas were negatively associated. Our results suggest the presence of bacterial interactions between Campylobacter and the broiler litter microbiome. The negative association of Campylobacter with Bifidobacterium, Anaerosporobacter, and Stenotrophomonas in litter could be potentially exploited as a pre-harvest control strategy.

Interrelationships of Chemical, Physical and Biological Soil Health Indicators in Beef-Pastures of Southern Piedmont, Georgia

The study of interrelationships among soil health indicators is important for (i) achieving better understanding of nutrient cycling, (ii) making soil health assessment cost-effective by eliminating redundant indicators, and (iii) improving nitrogen (N) fertilizer recommendation models. The objectives of this study were to (i) decipher complex interrelationships of selected chemical, physical, and biological soil health indicators in pastures with history of inorganic or broiler litter fertilization, and (ii) establish associations among inorganic N, potentially mineralizable N (PMN), and soil microbial biomass (SMBC), and other soil health indicators. In situ soil respiration was measured and soil samples were collected from six beef farms in 2017 and 2018 to measure selected soil health indicators. We were able to establish associations between easy-to-measure active carbon (POXC) vs. PMN (R2 = 0.52), and N (R2 = 0.43). POXC had a noteworthy quadratic relationship with N and nitrate, where we found dramatic increase of N and nitrate beyond an inflection point of 500 mg kg−1 POXC. This point may serve as threshold for soil health assessment. The relationships of loss-on-ignition (LOI) carbon with other soil health indicators were discernable between inorganic- and broiler litter-fertilized pastures. We were able to establish association of SMBC with other soil variables (R2 = 0.76) and there was detectable difference in SMBC between inorganic-fertilized and broiler litter-fertilized pastures. These results could be useful for cost-effective soil health assessment and optimization of N fertilizer recommendation models to improve N use efficiency and grazing system sustainability.