Nan Xu

The phaseout of methyl bromide in agricultural production due to its adverse environmental impact has prompted specialty crop industry stakeholders to seek alternative soilborne disease management practices in the United States. Anaerobic soil disinfestation (ASD), recognized as a biological and environmentally friendly alternative, is considered a promising practice for managing soilborne pathogens, nematodes, and weeds. However, the economic feasibility of ASD in strawberry ( Fragaria × ananassa ) production remains underinvestigated. This study evaluated the economic viability of ASD using various application rates of carbon and nitrogen fertilizer sources in open-field organic strawberry production. Using field experiment data from production seasons 2022–23 and 2023–24 in Citra, FL, USA, the economic analysis demonstrated that although ASD treatments incur higher costs, the additional returns from increased yields of some treatments can offset these costs. Using 1486.0 gal/acre of molasses as the carbon source and 4.2 tons/acre of Everlizer (a heat-processed chicken litter product) as the nitrogen source in season 2022–23 produced the highest yield compared with the control group that did not use ASD in production. The same treatment in season 2023–24 produced the fifth-highest yield. When averaging the yields from both seasons, the same treatment still generated the highest added profit compared with the control group. Sensitivity analysis identified yield as the primary determinant of profit. Meanwhile, the profitability of strawberry production in treatment groups was highly sensitive to fluctuations in both strawberry selling price and molasses price. The findings of this study provide crucial information for strawberry producers to determine the economic viability of using ASD in organic crop production systems.

Sunn hemp (Crotalaria juncea L.), a warm season leguminous cover crop, is commonly used in rotation with organic strawberry production in Florida’s subtropical environment. This study was conducted to explore the impacts of sunn hemp on growth and yield performance of the subsequent organic strawberry crop in sandy soils, taking into consideration the nutrient contribution from soil incorporation of sunn hemp biomass. Sunn hemp was seeded during the summer off-season and terminated before flowering, three weeks prior to the fall planting of two strawberry cultivars (‘Strawberry Festival’ and ‘Camino Real’). With sunn hemp residues incorporated into the soil, two application rates of nitrogen (N) through pre-plant organic fertilization for the strawberry season were used, including N at a rate of 84 kg/ha, without consideration of the N credit from sunn hemp, and N at a rate of 19.8 kg/ha, with consideration of the estimated N credit from sunn hemp. A summer fallow without cover crop and with a pre-plant organic fertilizer application at the N rate of 84 kg/ha was included as the control. Overall, the sunn hemp incorporation at three weeks after termination did not benefit the strawberry plant growth or fruit yield in this study, with rather low levels of soilborne pathogen and nematode infestations. Both sunn hemp treatments exhibited a significantly lower level of total soil N compared to the summer fallow plots at the end of the strawberry season. The reduction in the pre-plant N fertilization resulted in lower above-ground plant dry weight and accumulation of N, phosphorus (P), and potassium (K) at the end of the strawberry season, along with fewer leaves and smaller crowns of the strawberry plants during the early season. Both sunn hemp treatments decreased early fruit yields, while the sunn hemp treatment with the reduced N fertilization also led to a significant reduction in the total fruit number and weight, although no significant differences in the whole-season marketable fruit yield were observed among the nutrient management treatments. Overall, ‘Strawberry Festival’ yielded higher than ‘Camino Real’, but the effects of nutrient management did not vary with the strawberry cultivars. Further studies are needed to enhance organic strawberry nutrient management involving rotational cover crops.

The addition of organic byproducts to soils is a vital source of essential nutrients for plant uptake. To reuse the nutrients effectively, there is a need to estimate the release patterns of nutrients from the byproducts. This study aimed to investigate the release patterns of nutrients [nitrogen (N), phosphorus (P), and potassium (K)] from bagasse, a sugarcane milling byproduct, at two soil depths (surface at 0 cm vs. buried at 15 cm) in sugarcane and fallow fields on two soil types (Histosols vs. Spodosols) in Florida. In addition, field incubation studies were conducted using the mesh bag technique for one year of sugarcane production. The nutrient release patterns and bagasse decomposition rates were determined under each scenario. The results indicated that bagasse decomposed faster when buried (totally decomposed after approximately 450 days) than when placed on the soil surface (about 50% remained after 450 days) in both sugarcane and fallow fields on Spodosols and Histosols. Bagasse decomposed faster in Histosols compared to Spodosols. N and P showed net immobilization after approximately one month of bagasse application when buried, which indicated additional N and P fertilizers should be considered to meet crop demand. K presented no immobilization, with a rapid initial release in Spodosols and a gradual release in Histosols.

Historical repository of UF/IFAS Extension numbered publications made available on the EDIS website. UF/IFAS Extension is a federal, state, and county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences and to making that knowledge accessible to sustain and enhance the quality of human life.

Anaerobic soil disinfestation (ASD) has been demonstrated as an effective alternative to pre-plant chemical soil fumigation (CSF) commonly used to control soilborne pathogens. However, the ASD effects on spatial and temporal changes in soil microbial communities remain poorly understood in production systems with low soilborne disease pressure. The objective of this study was to assess the influence of ASD treatments on soil microbial community composition at different soil depths during the spring tomato production season in Florida. Soil treatments included ASD using 6.9 m³ ha⁻¹ of molasses with 11 Mg ha⁻¹ of composted poultry litter (CPL) (ASD0.5), ASD with 13.9 m³ ha⁻¹ of molasses and 22 Mg ha⁻¹ CPL (ASD1.0), and chemical soil fumigation (CSF) using a mixture of 1,3-dichloropropene and chloropicrin. Soil microbial community composition was measured at soil depths of 0–15 and 15–30 cm using phospholipid fatty acid (PLFA) analysis at 0, 36, 76, and 99 days after transplanting (DAT). Fatty acid methyl esters were categorized into biomarker groups including total microbial biomass (TMB), G+ bacteria (G+), G− bacteria (G−), actinomycetes (Actino), arbuscular mycorrhizal fungi (AMF), protozoa, and general fungi (F). Soil concentrations of G+, Actino, F, AMF, and the ratio of F:bacteria (B) were significantly impacted by a soil treatment × soil depth × sampling time three-way interaction. All the microbial biomarkers were significantly affected by soil treatment × sampling depth two-way interactions except for protozoa and F:B ratio. Concentrations of TMB, Actino, AMF, F, G+, and G− bacteria were significantly increased in ASD treated soils at both 0–15 and 15–30 cm soil depths across different sampling times compared with CSF. In addition, the concentrations of G+ and G− bacteria, AMF, F, and TMB were higher at 0–15 vs. 15–30 cm soil depth under ASD treatments, whereas no soil depth differences were observed in CSF. Discriminant analysis further confirmed that soil microbial community composition was distinctly different in CSF compared with ASD treatments. The soil microbial profile was well-differentiated between the two soil depths under ASD treatments but not in CSF, while the enhancement of PLFA biomarkers by ASD decreased with increasing soil depth.

A standardized soil health scoring system would be a beneficial tool for accessing and interpreting the status of soil health in Florida. However, because of the climate variability and diverse soil types, a soil health soring function designed in one location may not be useful for other places. In this study, we focused on developing scoring functions for Florida soil using a soil health indicator database under different land management practices across Florida. A soil health scoring index for 11 soil health indicators was calculated for 398 soil samples using comprehensive assessment of soil health (CASH), linear or nonlinear scoring function, and additive and weighted‐additive methods. Based on communality and weights of total data sets (TDS), Mehlich‐3 phosphorus (M3P) contributed the most, whereas pH contributed the least to the indices. The nonlinear scoring function had higher scores than other scoring functions. Only mixed cropping systems had significant changes in soil health indicators before and after treatment. The principal component analysis (PCA) showed that OM and M3P had the highest loading values compared with other indicators. Therefore, OM and M3P need to be considered if minimum number of indicators is to be measured while examining soil health indices pertinent to Florida soil types and land management practices. Overall, the findings of this study provide a foundation for creating and enhancing soil health indices in Florida.

Regenerative farming is a common practice adopted to enhance soil health. Routinely, cheaply measured soil health indicators can be used to predict unknown soil health indicators, which makes analysis simple and fast. The objective of this study was to determine the interaction and relationship between soil health indicators and the effects of regenerative farming practices on soil health indicators. We conducted a comprehensive on‐farm study across Florida, measuring 11 soil health indicators for 592 soil samples that were collected from the surface 15 cm of soil on 13 experimental sites. Sampled fields were conventionally managed or subjected to either cover cropping, organic amendment application, or their combination, and fallow fields as control plots. We tested the Pearson correlation coefficient between 11 soil health indicators and further tested the types of relationships between each indicator using regression analysis. Strong positive correlations (r ≥ + .5 to 1.0) were obtained, especially between organic matter (OM) with maximum water holding capacity (MWHC), cation exchange capacity (CEC), soil protein (SP), and total Kjeldahl nitrogen (TKN); MWHC with CEC, SP, and TKN; TKN with CEC and SP; total phosphorus (TP) with Mehlich‐3 phosphorus (M3P). A strong negative correlation (r ≥ –.5 to –1.0) was observed between bulk density (BD) with OM, MWHC, CEC, and TKN. No significant change in soil health indicators was observed in control plots except for active carbon (AC) and CEC. Organic amendments and a combination of organic amendments with cover crops were effective in improving soil health indicators. However, cover crops alone had no effect on soil health indicators except for CEC and M3K.

The addition of agricultural by-products to mineral soils has the potential to improve crop production. This study aimed to determine the effects of the readily available sugarcane (Saccharum officinarum) milling by-product bagasse as a soil amendment on yields of sugarcane grown on a sandy Entisol of South Florida. The field trial was conducted on a commercial sugarcane farm for three annual crop cycles (plant cane and two ratoons). Four treatments including 5 cm bagasse (85 ton ha⁻¹); 10 cm bagasse (170 ton ha⁻¹); 10 cm bagasse (170 ton ha⁻¹) plus 336 kg ha⁻¹ ammonium nitrate; and a control (without bagasse and ammonium nitrate) were evaluated. Results indicate that one single application of bagasse increased sugarcane biomass and sugar yield by approximately 23% in the plant cane year. A higher application rate of bagasse (10 cm of bagasse) was recommended since it had a longer effect on increasing sugarcane biomass and sugar yield. Bagasse application enhanced silicon (Si) supply and increased Si plant nutrition. However, the effects of bagasse on the other leaf nutrients were not significant.

Conventional cropping systems on sandy soils require continuous application of large amounts of external nutrients and irrigation water yet remain vulnerable to loses of these inputs. Within the state of Florida, need exists to provide farmers with economically viable alternatives that harness ecological processes and improve soil health and biodiversity. Cover crops are proving to be vital in the development of soil health. As part of this study we conducted a comprehensive on-farm assessment involving nine collaborative growers (ten farms) across the state; with each individual farm following its unique cover-cropping practice. Our goal was to shadow their practice and determine its effect on soil health indicators such as soil pH, bulk density (BD), maximum water holding capacity (MWHC), organic matter (OM), active carbon, cation exchange capacity, soil protein, Total Kjeldahl nitrogen (TKN), total phosphorus (TP), Mehlich-3 P (M3P) and potassium (M3K). Compared to fallow, soil OM, MWHC, and soil protein showed increases in cover crop fields for most farms, which presented a positive change towards building up soil health. Although soil TKN level was significantly decreased due to cover crops, soil protein level building up over time was the most positive change for soil health. M3K decreased in cover-crop fields, which indicated that supplementary K would be necessary prior to planting subsequent cash crops.

The addition of organic amendments and cover cropping on sandy soils are regenerative farming practices that can potentially enhance soil health. South Florida mineral soils present low soil quality due to their sandy texture and low organic matter (OM) content. Few studies have focused on evaluating the effects of farm-based management regenerative practices in this region. The objective of this study was to evaluate changes in soil properties associated with two regenerative farming practices - horse bedding application in combination with cover cropping (cowpea, Vigna unguiculata), compared to the practice of cover cropping only for two years. The soil quality indicators that were tested included soil pH, bulk density, water holding capacity, cation exchange capacity, OM, active carbon, soil protein and major nutrients (N, P, K). Results indicated no significant changes in soil pH, but a significant reduction in soil bulk density and a significant increase in maximum water holding capacity for both practices. Cation exchange capacity and the amounts of active carbon increased significantly after 1.5-year of the farming practices. Horse bedding application with cover cropping showed a significant 4% increase in OM during a short period. A significant increase in plant-available P was also observed under these two practices. Based on this study, horse bedding application as an organic amendment in conjunction with cover cropping provides an enhanced soil health effect compared to just cover cropping. As local growers explore farming option to improve soil health particularly during the fallow period using regenerative farming practices on sandy soils, these results will assist in their decision making.