About

Luciano Gatiboni is a professor and extension specialist in soil fertility and nutrient management at NC State University. He teaches Soil Fertility in the Graduate Program in Soil Science and leads an applied research and extension program focused on North Carolina cropping systems. His program aims to develop and refine soil test-based nutrient and lime recommendations to maximize yields and profitability while minimizing nutrient losses. Dr. Gatiboni conducts studies on soil test correlation and calibration, the impact of saltwater intrusion on cropping yields, and crop responses to lime and gypsum application. His extension activities include producing publications and providing technical support and training to extension agents, crop consultants, and farmers in North Carolina.

Research topics

• Biology
• Agronomy
• Chemistry
• Environmental science
• Ecology
• Soil science
• Chromatography
• Biochemistry
• Horticulture
• Agroforestry
• Mathematics
• Environmental chemistry

Selected publications

• Reference Nutrient Levels in Soil and Leaves for Vines Cultivated in a Subtropical Climate Using Boundary Line

  Journal of soil science and plant nutrition · 2026-03-16

  articleOpen access

  The study aimed to establish nutritional reference values in the soil and leaves of Vitis spp. vines, cultivated in a subtropical climate to obtain high yield, using the boundary line (BL) method. The research was conducted in the 2021/22 and 2022/23 harvests, in the Serra Gaúcha region, Southern Brazil, one of the main winemaking regions in South America. Six cultivars were evaluated: four Vitis labrusca (‘Isabel’, ‘Bordô’, ‘BRS Magna’, and ‘BRS Lorena’) and two Vitis vinifera (‘Pinot Noir’ and ‘Chardonnay’). A total of 207 vineyards were evaluated, and seven plants were selected and marked in each vineyard. Complete leaves (blades + petiole) opposite to the bunch were collected to evaluate total nutrient contents during flowering. At harvest, soil samples (0.00–0.20 m layer) were collected for soil fertility evaluation, and the number of bunches was counted to estimate yield. The relative fruit yield (RFY) was related to soil chemical attributes and foliar nutrient contents through scatter plots, using the BL method to obtain soil fertility classes and nutrient sufficiency ranges. The sufficiency ranges considered adequate in the soil for pH(H2O), soil organic matter, P, K, Ca, Mg, Cu, Zn, Mn, CECpH7.0, and Ca-Mg-K saturation were proposed. Also, the nutrient sufficiency ranges in the leaves for N, P, K, Ca, Mg, S, Cu, Zn, Fe, Mn, and B were defined. These results will contribute to greater accuracy in fertilization, maintenance of high grape yields, reduction of environmental impacts from excess fertilizers, and reduction of viticulture production costs.

  PublisherOA PDFDOI

• Phosphorus recommendations in Brazil and Paraguay: A systematic review

  Soil Science Society of America Journal · 2026-03-01

  articleOpen accessCorresponding

  Abstract Fertilizer recommendation systems in Brazil and Paraguay are based on soil analysis and correlation‐calibration experiments; however, they often recommend divergent phosphate fertilizer rates for the same crop and yield target. This study compares phosphate fertilizer recommendation systems for soybean [ Glycine max (L.) Merr.], wheat [ Triticum aestivum (L.)], and maize [ Zea mays (L.)], using standardized yield targets of 3, 4, and 10 Mg ha −1 , respectively. Eleven regional recommendations were evaluated: ten from Brazil and one from the Eastern Region of Paraguay. Most systems use the Mehlich‐1 method to extract available P, except São Paulo, which uses an anion exchange resin. The widespread use of Mehlich‐1 allows comparison of critical soil test values (CSTV) of P across tropical and subtropical soils. In several systems, CSTV declines with increasing clay content, likely due to extractor limitations and P readsorption during decantation, yet few recommendations explicitly incorporate P sorption capacity (e.g., clay content) when defining rates. Differences among calibration experiments have resulted in a wide range of CSTV (4–56 mg dm −3 ) and recommended P 2 O 5 rates of 82–415 kg ha −1 for soybean (≈36–181 kg P ha −1 ), 87–329 kg ha −1 for wheat (≈38–144 kg P ha −1 ), and 118–362 kg ha −1 for maize (≈52–158 kg P ha −1 ). Mehlich‐1 thresholds above which phosphate fertilization becomes unnecessary also varied widely (5–35, 3–37, and 6–46 mg dm −3 for soybean, wheat, and maize, respectively). These results highlight the need for minimum guidelines to harmonize soil P test interpretation and phosphate fertilizer recommendations, improving P use efficiency in Brazil and Paraguay.

  PublisherDOI

• Why Does Overapplication of Phosphorus Fertilizers Occur: Insights from North Carolina Farmers

  Agriculture · 2025-03-12 · 2 citations

  articleOpen access

  To minimize environmental damage, conserve global diminishing fertilizer reserves, all while maximizing food production, it is essential that farmers apply phosphate fertilizers at the optimal rate. The purpose of this study is to assess grower attitudes and behavior, with respect to proper application of phosphorus, and to investigate how certain exogenous factors might influence such applications. Data were analyzed from a survey conducted in North Carolina, USA, with 122 farmer participants. The findings reveal that annual phosphorus applications consistently exceed recommendations, which indicates overapplication, leading to economic inefficiency and environmental concerns. Overapplication is neither due to knowledge gaps in nutrient concentrations in the soil nor the lack of interest in soil sampling, as 99% of farmers submit soil tests as frequently or more frequently than every two years. Only 36% of growers indicated that they would not apply phosphorus if their soil report indicated that levels were sufficient, and that none was required. Additionally, overapplication is not strongly influenced by price effects, as only nine percent of growers abandoned applications in 2021, following a dramatic spike doubling fertilizer prices. The adoption of reduced phosphate fertilization will depend on strong local trusted technical assistance and continued extension education.

  PublisherOA PDFDOI

• Phosphate fertilization strategies and placement effects on grain crop yields in subtropical no-till Oxisols

  Revista Brasileira de Ciência do Solo · 2025-01-01

  articleOpen access

  ABSTRACT Subtropical Oxisols have a high phosphate adsorption capacity and consequently lower phosphorus (P) availability. Therefore, correct management of phosphate fertilization in grain crop rotations is essential to increase the P-use efficiency and minimize potential environmental impacts. This study aimed to evaluate, in soils with medium and high initial P level, fertilization strategies (crop and system fertilization) and placement’s effects (banded P and broadcast) on soil available P, crop yield, and P use efficiency. Two field trials were installed on an Oxisol (Humic Hapludox – Latossolos) cultivated with a crop rotation with corn or soybean in the summer, and cereals in the winter. Crop yield, P use efficiency, and soil available P in the 0.00-0.10 and 0.10-0.20 m layers were evaluated during eight growing seasons. Three years of phosphate fertilization increased the P content of the 0.00-0.20 m layer above the critical level (8 mg dm - ³) in the soil with medium initial P and maintained the P status above the critical level in the soil with high initial P. The P-rich environment in the 0.00-0.10 m soil layer was sufficient to support high-yield grain crops with low response to fertilization strategies and placement. However, four years of banded P fertilization on high initial P soil resulted in a greater increase in P content in the 0.10-0.20 m layer compared to broadcast P. In the field trial with medium initial available P content, there was a greater response to phosphate fertilization, leading to a significant increase in grain yields when compared to the control treatment with no P, especially for barley (50 % increase). Over four years of evaluation, banded P, regardless of the fertilization strategy (crop or system), proved effective in increasing crop yield (for one crop of black oat and three crops of corn) and P use efficiency (one crop of corn). System fertilization in a high P export environment should be adopted only in soils with available P content above the critical level and after at least four years of using diverse winter cover crops (grass + legume). Otherwise, P fertilization at every sowing (crop fertilization) remains more appropriate for intense grain production systems.

  PublisherOA PDFDOI

• Accumulation of phosphorus fractions in contrasting soils under long‐term phosphate fertilization

  Journal of Environmental Quality · 2025-12-11

  articleOpen accessCorresponding

  Abstract Understanding phosphorus (P) dynamics in soils under conservation agriculture remains challenging because the long‐term effects of fertilization rates and soil texture on P accumulation, availability, and environmental risk are not being fully understood. This study evaluated P fraction accumulation and saturation indices across soil layers in response to increasing phosphate fertilizer rates in two long‐term experiments in North Carolina. The trials were conducted on Portsmouth soil (fine‐loamy over sandy or sandy‐skeletal, mixed, semiactive, thermic Typic Umbraquults) at Tidewater, managed under minimum tillage, and Lloyd soil (fine, kaolinitic, thermic Rhodic Kanhapludults) at Piedmont, under no‐tillage. Soil samples from 0‐ to 5‐cm, 5‐ to 10‐cm, 10‐ to 20‐cm, and 20‐ to 30‐cm depths were analyzed in 2022 using sequential chemical fractionation and P‐related indices, including P sorption and degree of P saturation (DPS). Most P fractions were significantly influenced by P rates and depth. In clayey Piedmont soil, occluded P reached 58% of total P and increased linearly with rates (up to 30 cm). Sandy Tidewater soil showed higher soluble P (up to 4 mg kg −1 at 0–5 cm) and DPS values reaching 40%, signaling environmental risk. The DPS index proved sensitive to increasing P fertilization, outperforming the P sorption index. Mehlich‐3 P exceeding 169 mg kg −1 in sandy soil indicates a contamination risk threshold due to elevated soluble P. Different behaviors of P fractions, especially occluded P, highlighted the importance of soil‐specific fertilization strategies and considering P saturation as essential for optimizing P use and mitigating environmental impacts. The DPS index emerges as a valuable tool for assessing fertilization history and guiding P management strategies.

  PublisherOA PDFDOI

• Effect of model choice on critical soil test value of phosphorus for corn in long‐term trials in North Carolina

  Soil Science Society of America Journal · 2025-07-01 · 3 citations

  articleOpen accessCorresponding

  Abstract The soil test correlation determines the critical soil test value (CSTV) of phosphorus (P) required to achieve 95%–100% of the maximum crop yield. However, CSTV predictions vary with the mathematical model used, which has implications for fertilizer recommendations. This study compared the P CSTVs for corn ( Zea mays ) estimated using four models, (1) modified arcsine‐log calibration curve (ALCC), (2) linear plateau (LP) at the join point (JP), (3) quadratic plateau (QP) at the JP (QP‐JP), and (4) QP at 95% of maximum yield (QP‐95), and then calculated the frequency of crop response at different Mehlich‐3 soil test phosphorus (STP) concentrations. Corn was grown in long‐term trials in 2010, 2012, and 2014 in the Piedmont, Coastal Plain, and Tidewater regions of North Carolina. The P CSTVs obtained with ALCC, LP‐JP, QP‐JP, and QP‐95 models were 42, 24, 31, and 26 mg kg −1 , respectively, at the Coastal Plain site and 55, 43, 55, and 49 mg kg −1 at the Tidewater site, but these models could not calculate CSTVs at the Piedmont site. Nevertheless, the 95% confidence interval of CSTV did not differ for these models and sites analyzed. The frequency of corn response to STP declined with increasing STP, reaching 10% at 37.0 and 44.9 mg kg −1 at Coastal Plain and Tidewater sites, respectively, defining critical soil test range (CSTR) of 26–37 and 45–49 mg kg −1 . Additional approaches combined with CSTV using broader datasets may help to refine the CSTR definition and improve fertilizer recommendations.

  PublisherOA PDFDOI

• The Fertilizer Recommendation Support Tool: A relational database and decision interface tool

  Agricultural & Environmental Letters · 2025-04-20 · 3 citations

  articleOpen access

  Abstract The Fertilizer Recommendation Support Tool (FRST) Project is a collaborative effort involving most land grant institutions, USDA branches, nonprofit organizations, and private industry. The FRST objectives are to develop a soil fertility community of practice, preserve soil test correlation and calibration data in a relational database, and develop a decision tool to provide consistent soil test interpretations. Released in April 2024, the interactive tool acts on an evolving database that contained 1455 P trials, 1316 K trials, and 143 S trials from 44 states and Puerto Rico by March 1, 2025. Decision tool outputs include an interactive county‐level map of available data and an estimated critical soil test value. The FRST relational database is a repository for soil‐test‐based P, K, and S data to support data‐driven management recommendations. Continued success of the FRST project and decision tool utility rely on collaboration and support from the soil‐test‐based nutrient management community.

  PublisherOA PDFDOI

• Drawdown of soil phosphorus by crop removal: A meta‐analysis of 56 fields with interrupted fertilization

  Agricultural & Environmental Letters · 2025-01-03 · 5 citations

  articleOpen access1st authorCorresponding

  Abstract Phosphorus (P) is an essential nutrient applied as fertilizer in agricultural fields. However, excessive fertilization leads to P build up in soils, increasing its potential to cause environmental pollution. The objective of this study was to evaluate the average P drawdown rate of 56 sites with drawdown management presented in 14 publications. Soil test P (STP) results were converted to Mehlich‐3 equivalent and resampling analysis was used to compare the annual drawdown rate in fields grouped by four initial STP classes. The STP was reduced by 4.3%–8.2% per year, depending on the initial STP class. It took from 8.4 to 15.9 years to reduce the STP by half. The resulting equations from this meta‐analysis can be used by landowners to estimate the time needed for STP drawdown by cropping without additional P to achieve the desired STP concentration. Core Ideas Cropping without phosphorus (P) fertilization is one of the few options to reduce soil test P (STP). A meta‐analysis of the annual P drawdown rate was performed using 56 sites presented in 14 publications. Fields were grouped into four initial STP classes based on Mehlich‐3 STP equivalent. The STP was reduced from 4.3% to 8.2% per year in fields with high and low initial STP. The time needed to reduce the STP by half varied from 8.4 to 15.9 years depending on the initial STP.

  PublisherOA PDFDOI

• Transport of Phosphorus from Three Fertilizers Through High- and Low-Phosphorus Soils

  Agronomy · 2025-10-15 · 2 citations

  articleOpen access

  Chemical fertilizers are commonly used to supply phosphorus and other nutrients to crops, but due to high affinity of soils for P fixation, over-application of P fertilizer is common, which may result in groundwater and surface water pollution. To increase P use efficiency, different strategies, including different fertilizer formulations and types, have been developed. Two struvite-based fertilizers, Crystal Green® (CG) and Crystal Green Pearl® (CGP), are touted as environmentally safe, because they are insoluble in water but soluble in organic acids exuded from crop roots. The objective of this study was to assess fate and transport of P from diammonium phosphate (DAP), CG, and CGP through two loam soils with a significant difference in their initial P content. Two loamy soils, one collected from an experimental field receiving fertilizer continuously since 1985 and one from an adjacent area receiving no fertilizer, and a pure sand control were packed in 5 cm diameter and 5 cm long columns. Several grains equivalent to approximately 80 mg P from each fertilizer were imbedded at the bottom of the column. Distilled water was passed through the soil columns from the bottom at a relatively constant rate, and the outflow was collected every two hours using a fraction collector. Outflow samples from each treatment combination were analyzed for P by the colorimetric method, and the amount of P retained by the soils along the column at the end of the water application was determined by the nitric acid digestion method. Approximately 91% of P in DAP, 34% in CG, and only 3.8% in CGP was transported through the sand column. In contrast, the amounts of P transported were approximately 42.2% for DAP, 6.4% for CG, and 0.4% for CGP through the high-P soil and 22.4% for DAP, 0.6% for CG, and almost zero for CGP through the low-P soil. Overall, the results show a high solubility and transport for DAP, very low transport for CGP, and somewhat low to medium transport for CG fertilizers. In addition, the results show that even the high-P soil that has received fertilizer for about 40 years has the capacity to fix significant amounts of P.

  PublisherOA PDFDOI

• Endomycorrhizal inoculant evaluation on soybean in North Carolina under varying potassium levels

  Agronomy Journal · 2025-09-01

  article

  Abstract Potassium (K + ) is a key macronutrient for plant growth. While arbuscular mycorrhizal (AM) fungi have been shown to enhance K + uptake in model legumes like barrel medic ( Medicago truncatula ), their effect on crop legumes such as soybean [ Glycine max (L.) Merr.] is not well documented. A 2‐year field study across three North Carolina regions assessed the impact of AM inoculation on soybean growth, nutrient uptake, yield, and seed quality. Trials targeted soils low in phosphorus and K + , using K + chloride to establish high (67 kg ha −1 ) and low (0 kg ha −1 ) K + environments. Three commercially available soybean cultivars (maturity groups IV, V, and VI) were either inoculated with AM fungi or left untreated. Measurements at 10 and 16 weeks post‐planting included chlorophyll content estimation, shoot biomass, and tissue nutrient concentrations. Results indicated that environmental conditions and cultivar maturity group had the strongest influence on biomass, K + uptake, yield, protein, and oil content. AM inoculation had limited impact across treatments. These findings, consistent with previous studies, suggest that AM inoculation offers minimal practical benefit for soybean K + nutrition under field conditions in North Carolina. Growers should critically evaluate product claims and use caution when adopting AM inoculants expecting significant yield improvements.

  PublisherDOI

Frequent coauthors

• Gustavo Brunetto

  102 shared

• Djalma Eugênio Schmitt

  Universidade Federal de Santa Catarina

  63 shared

• João Kaminski

  40 shared

• Daniel João Dall’Orsoletta

  33 shared

• Danilo Rheinheimer dos Santos

  33 shared

• Gilmar Luiz Mumbach

  Universidade do Estado de Santa Catarina

  32 shared

• Jucinei José Comin

  27 shared

• Paulo Roberto Ernani

  26 shared

Labs

• Crop and Soil SciencesPI

Education

• Ph.D., Soil Science

  University of California, Davis

  1990

• M.S., Soil Science

  University of California, Davis

  1986

• B.S., Soil Science

  University of California, Davis

  1983