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Potassium (K) deficiencies in irrigated soybean [Glycine max (L.) Merr.] are common in irrigated mid-South production systems that can limit soybean yield potential. A study was conducted to correlate the relative soybean grain yield to the leaf-K concentration at 15 days after first flower (DAR1) and calibrate the fertilizer-K rate needed to correct in-season K deficiencies and maximize grain yield at 15 DAR1 based on the trifoliolate leaf-K concentration. Research was conducted in 2021 and 2022 at 8 site-years across Arkansas on silt loam soils planted with maturity group 4 or 5 cultivars. One treatment received 160 lb K2O/ac as granular muriate of potash (MOP) at preplant, and all other treatments received no preplant fertilizer-K followed by multiple rates of granular MOP ranging from 0 to 160 lb K2O/ac at 15 DAR1. The trifoliolate leaf-K concentration was measured in the upper-most fully expanded leaf at 15 DAR1 and was confirmed to be positively correlated with relative grain yield. Soybean leaf-K concentrations ranged from 0.96% to 1.93% K at 15 DAR1. Soybean with leaf-K concentrations at or less than 1.76% K at 15 DAR1 responded significantly to in-season fertilizer-K applications. Quadratic models were used to predict the fertilizer-K rate needed to reach 95% relative grain yield or the highest relative grain yield achieved for the responsive sites, which ranged from 20 to 120 lb K2O/ac depending on the leaf-K concentrations. Calibrated fertilizer-K rates based on tissue-K concentrations in early reproductive growth will enable producers to correct deficiencies in season with the appropriate fertilizer rate to maximize yield. [ABSTRACT FROM AUTHOR]

Nitrogen (N) fertilizer is essential to maximize cotton (Gossypium hirsutum) yield in most fields across Arkansas, and research regarding optimal rates and timings is limited. Small-plot N response trials were implemented on silt loam soils at the University of Arkansas System Division of Agriculture's Lon Mann Cotton Research Station (LMCRS) and Rohwer Research Station (RRS) in 2023. The cotton cultivar DP 2020 B3XF was planted at both locations, and the cultivar DP 2038 B3XF was also planted at the RRS adjacent to the first cultivar. The six N fertilizer treatments included a nontreated control and a split application of 30 lb N/ac applied preplant and incorporated, followed by 90 lb N/ac sidedress to represent a low and high check, respectively. The four additional N applications were made at the first square growth stage and were applied as sidedress applications of 40, 80, 120, and 160 lb N/ac. The Arkansas Extension recommendation for the production region is 110 lb N/ac. Cotton was managed using Cooperative Extension Service recommendations, and yield was determined using a small plot cotton picker and an assumed turnout of 41%. Cotton lint yields at the LMCRS were excellent, reaching >1115 lb/ac for all treatments, and the cotton was responsive to N fertilizer application. At the RRS, cotton yields were suboptimal (<670 lb/ac) but similar to reports from previous years, with only a significant yield response observed in the DP 2020 B3XF cultivar. Yield results for the LMCRS indicate that 80 lb N/ac (yield of 1613 lb /ac) or 30 lb N/ac applied preplant and incorporated, followed by 90 lb N/ ac sidedress (yield of 1603 lb/ac.) can be used effectively. These results suggest that N management in cotton can be refined to provide producers with additional options and that in-season N applications can be sufficient to maximize cotton yield potential with no preplant N. [ABSTRACT FROM AUTHOR]

Potassium (K) is one of the most limiting nutrients for rice (Oryza sativa L.) grown in the direct-seeded, delayed-flood production system common in the U.S. Mid-South and substantial yield reductions can occur when produced on soils low in exchangeable K. The primary objective of our research was to compare yield responses of pure-line and hybrid rice cultivars to K fertilization in a trial where various K rates (0, 40, 80, 120, and 160 lb K2O/ac) have been applied annually for several years. With Very Low (<61 ppm) Mehlich-3 K in the no-fertilizer-K control plots, both cultivars responded to K fertilization. Without K application, the pure-line (Diamond) produced 67% of the maximum yield produced when fertilized with K, while the hybrid (RT 7321 FP) produced 53% of the maximum yield. Averaged between cultivars, grain yields of 107, 145, 155, 167, and 177 bu./ac, which were all significantly different, were produced from annual application rates of 0, 40, 80, 120, and 160 lb K2O/ac, respectively. Grain yields were significantly less from the hybrid (135 bu./ac) than from Diamond (165 bu./ac), averaged among fertilizer-K rates, but the interaction of cultivar and K rate did not influence yields. Grain yields of the hybrid cultivar were lower than expected, likely due to lodging, which decreased as fertilizer-K rate increased. Results of this study suggest that RT 7321 FP may be more responsive to K fertilizer than pure-line cultivars, but recent trials observed another hybrid (RT Gemini 214 CL) to be less responsive. Based on inconsistent responses of hybrid rice to K fertilization and the fact that earlier studies predominantly evaluated pure-line cultivars, it is important to continue studying the response of hybrid rice to K fertilization to build a database for proper interpretation of tissue data and potential adjustments to K fertilizer recommendations. [ABSTRACT FROM AUTHOR]

Corn (Zea mays L.) grain yield is tightly linked to potassium (K) fertilization practices, but so is producer profitability. Work sponsored by the Arkansas Corn and Grain Sorghum Board has been ongoing to verify the current K fertilization rates based on soil test K concentrations and develop leaf tissue correlation and concentration data to diagnose in season K deficiencies. Potassium response trials were established at four research stations across Arkansas in 2022 and included the Milo J. Shult Agricultural Research and Extension Center (SAREC), the Lon Mann Cotton Research Station (LMCRS), the Pine Tree Research Station (PTRS), and the Rohwer Research Station (RRS). Six K fertilizer rates ranging from 0-200 lb K2O/ac were applied preplant and incorporated prior to corn establishment. At the VT growth stage earleaf (leaf immediately subtending the ear) samples were collected, dried, ground and analyzed to determine tissue-K concentration. At maturity corn grain yield was determined using a small plot combine. Preplant soil samples suggested that the PTRS location should be highly responsive to K fertilizer applications, that LMCRS would have little to no response to K fertilization and that SAREC and RRS should not respond to K fertilization. Yield results indicated a significant yield increase from K fertilization at the LMCRS and the PTRS with yield increases of 14 and 83 bu./ac, respectively. Corn earleaf tissue-K concentrations ranged from 0.79% to 2.67 % K and were not statistically different than one another at the SAREC or RRS locations but were influenced by K fertilizer rate at LMCRS and PTRS. The results of this trial suggest that corn response to K fertilization in Arkansas can be significant and that earleaf tissue-K concentrations can be a good indicator of K nutritional status. [ABSTRACT FROM AUTHOR]

Recent advancements in soil testing and plant analysis have expanded potassium (K) management in soybean [Glycine max (L.) Merr.] from traditional preplant applications based simply on soil test results to also include profit-maximizing K rates using the economic potash rate calculator and in-season diagnosis of hidden hunger using tissue tests. The objective of this research was to validate K management strategies available for soybean, including traditional preplant applications, a reduced preplant rate according to the economic potash rate calculator, in-season granular fertilizer-K applications, in-season foliar fertilizer-K applications, and split fertilizer-K applications. The research was conducted as a randomized complete block design in 2022 on a Henry silt loam with Very Low soil-test K (STK). The site experienced dry weather and delayed irrigation, resulting in visual K deficiencies 15 days after R1 stage (DAR1), confirmed by trifoliolate leaf samples collected at 15 DAR1. The deficiencies were remediated by irrigation and in-season applications of granular fertilizer K. Regardless of the granular fertilizer-K rate, the addition of a foliar K source applied 2 gal/ac (4.6 lb K2O/ac) at 30 DAR1 did not significantly increase grain yield. Additionally, there was no significant yield difference when the same rate of granular fertilizer-K was applied all preplant compared to one-half preplant and one-half 15 DAR1. However, treatments that received additional in-season granular fertilizer-K applications did numerically outyield those which did not. Finally, the yield-maximizing K rate based on soil test values and the profit- maximizing K rate based on fertilizer and grain prices at the time of planting resulted in similar yields. Therefore, both the traditional yield-maximizing K rate and the reduced profit-maximizing K rate are successful management approaches when applied all at preplant or as split applications to include in-season granular fertilizer-K applications. [ABSTRACT FROM AUTHOR]

The goals of this research project are to determine the dry matter production and yield of two modern cotton cultivars (Deltapine 2038 and NexGen 4936) grown in a furrow-irrigated system that is typical of eastern Arkansas production. The study was replicated at three different site years: in 2021 at the University of Arkansas System Division of Agriculture's Lon Mann Cotton Research Station (LMCRS), and in 2022 at the Lon Mann Cotton Research Station and at the Rohwer Research Station (RRS). The 2021 site year was planted on a Zachary silt loam, while the 2022 Lon Mann Cotton Research Station site year was planted on a Convent silt loam, with the 2022 Rohwer Research Station site year on a Sharkey and Desha silt loam. Treatments included two different rates of fertilizer designed to apply 100% and 125% of current University of Arkansas Soil Test Laboratory fertilizer rate recommendations for nitrogen (N), phosphorus (P), and potassium (K) based on soil test nutrient levels where applicable. Fertilizer treatments were applied preplant and at early squaring. For the 100% rate, the sum of the fertilizer treatments was applied as follows: 2021 LMCRS 70 lb P2O5, 60 lb K2O, 110 lb N; 2022 LMCRS 50 lb P2O5, 95 lb K2O, 110 lb N; 2022 RRS 50 lb P2O5, 40 lb K2O, 110 lb N. The sum of the fertilizer treatments applied for the 125% rate were as follows: 87.5 lb P2O5, 75 lb K2O, 137.5 lb N; 2022 LMCRS 62.5 lb P2O5, 119 lb K2O, 137.5 lb N; 2022 RRS 62.5 lb P2O5, 50 lb K2O, 137.5 lb N. Preliminary results show no difference between either the cultivars or the fertilizer treatments. Total averaged aboveground biomass for the first sample time of the year (10 days after emergence) ranged from 11 lb/ac to 33 lb/ac, while the final sample time (at the start of the defoliation period) ranged from 1594 lb/ac to 2722 lb/ac. Lint yields averaged across cultivars and fertilizer treatments within each site year ranged from 427 to 2249 lb/ac. [ABSTRACT FROM AUTHOR]

Recent advancements for in-season potassium (K) management in soybean [Glycine max (L.) Merr.] allows the diagnosis of deficiencies at any point during reproductive growth. However, the rate of fertilizer-K necessary to correct the various levels of deficiency defined by trifoliolate leaf tissue-K concentrations to achieve maximum yield remains unknown, especially as the season progresses. Therefore, our primary objectives were to correlate the trifoliolate leaf-K concentrations with soybean relative grain yield and to calibrate K-fertilizer rates with leaf-K concentrations to create rate recommendations to achieve 95% relative grain yield based on the leaf tissue-K concentrations and days after R1 (DAR1). Treatments included multiple rates of granular muriate of potash at 15 DAR1, 30 DAR1, and 45 DAR1. The research was conducted in 2021 at the University of Arkansas System Division of Agriculture's Lon Mann Cotton Research Station near Marianna, Ark., on silt loam soil. The results indicate that maximal yield can be recovered from a deficient crop at 15 DAR1, a positive yield response can be recovered from a deficient crop at 30 DAR1, and little yield response was observed when fertilizer-K was applied at 45 DAR1. Therefore, in-season applications are effective at maintaining yield if applied during early reproductive growth. However, a delay in application timing may jeopardize yield potential to the degree that correcting it is no longer profitable, especially when the K deficiency is severe. Calibrated K rates based on tissue-K concentrations for a given growth stage will enable producers to correct deficiencies in-season with the appropriate fertilizer rate to maximize yield and profit. [ABSTRACT FROM AUTHOR]

The method to collect a representative sample can be used to accurately diagnose in-season soybean [Glycine max (L.) Merr.] potassium (K) deficiencies rely on the spatial variability of trifoliolate tissue-K concentrations within a field. Five commercial soybean fields were sampled at a 1-acre grid resolution throughout reproductive growth to quantify the trifoliolate tissue-K concentration. The objectives of this study were to identify the potential field variability in soybean leaf tissue-K concentrations in typical Arkansas soybean production systems and develop a sampling protocol for in-season tissue monitoring. No spatial dependencies were found in all fields and sample times, indicating that leaf samples should be collected according to the producer's preferred management strategy instead of specific grid size. One composite sample consisting of at least 18 of the upper-most fully expanded trifoliolate leaves from throughout the delineated management zone is needed to capture the average leaf tissue-K concentration. This sampling protocol, coupled with the newly developed dynamic critical tissue-K concentration curve, will allow producers to effectively monitor soybean for potential hidden hunger and verify K deficiency symptoms in season. [ABSTRACT FROM AUTHOR]

Potassium (K) is one of the most limiting nutrients for rice (Oryza sativa L.) grown in the direct-seeded, delayed-flood production system common in the U.S. mid-South, and substantial yield reductions can occur when produced on soils low in exchangeable K. The primary objective of our research was to compare yield responses of pure-line and hybrid rice cultivars to K fertilization in trials where various K rates (0, 40, 80, 120, and 160 lb K2O/ac) have been applied annually for several years. Whole, aboveground plant samples were collected at 50% heading in 2020 and Y-leaf samples were collected at the booting growth stage in 2021. With Very Low (<61 ppm) Mehlich-3 K in the control plots, both cultivars responded to K fertilization in 2020 and 2021. Without K fertilization, the pure-line (Diamond) produced 75% and 69% of the maximum yield produced when fertilized with K, while the hybrids produced 64% (RT 7521 FP) and 39% (RT 7321 FP) of maximum yields. For Diamond, the relationship between yield and tissue-K concentration was consistent with critical concentrations suggested by previous research. Grain yields of the hybrid cultivars, however, were lower than expected based on tissue-K concentrations and may indicate a difference in the responsiveness of hybrid and pure-line cultivars to K fertilization. Results of this study suggest that the two hybrids (RT 7521 FP and RT 7321 FP) may be more responsive to K fertilizer than pure-line cultivars, but recent trials have shown another hybrid (RT Gemini 214 CL) to be less responsive than pure-line cultivars. Based on inconsistent responses of hybrid rice to K fertilization and the fact that earlier studies predominantly evaluated pure-line cultivars, it is important to continue studying the response of hybrid rice to K fertilization to build a database for proper interpretation of tissue data and potential adjustments to K fertilizer recommendations. [ABSTRACT FROM AUTHOR]

Corn grain yield is closely linked to N fertilization practices, but so is producer profitability. Research to verify the capabilities of aerial imagery and dark green color index (DGCI) to successfully identify corn tissue N concentration is ongoing. The ability of DGCI via remote imagery to predict corn response to N fertilization has been further validated in the three site years included in this trial. There is a strong relationship between the N rate and corn DGCI value, with the DGCI properly predicting the sufficient tissue N concentration at the V10 and V13 growth stages. Although the data set is limited, a N rate calibration curve based on the tissue N concentration across corn growth stages (V10-VT) to predict in-season N fertilizer rates to maximize corn grain yield is being developed. The successful development of these calibration curves will allow producers to apply site-specific, in-season N fertilizer rates to ensure that their corn grain yields are being maximized. At the V10 growth stage, significant increases in corn grain yield were seen when tissue N concentrations were less than 3.5%N. However, the yield gains from in-season N applications at V10 ranged from 14-100 bu./ac. Similarly, corn grain yield responses to in-season N applications were observed when tissue N concentrations were less than 3.0% N at both the V13 and VT growth stages. Increased N application rates were required to maximize corn grain yield at lower tissue N concentrations at each growth stage and ranged from 45-150 lb N/ac. Additional data will help to refine these in-season N rate predictions based on tissue N concentrations. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) cultivars grown in the Arkansas Delta have undergone tremendous genetic and cultural management changes in recent years, which has led to the need to re-evaluate the biomass, nutrient accumulation, and nutrient requirements in these modern cultivars. Our research aims to determine the dry matter production and biomass accumulation of two modern cotton cultivars (Deltapine 2038 and NexGen 4936) produced in a furrow-irrigated system. Treatments included two rates of fertilizer designed to apply 100% and 125% of the current University of Arkansas System Division of Agriculture's Soil Test Laboratory fertilizer rate recommendations for nitrogen (N), phosphorus (P), and potassium (K). Fertilizer treatments were applied preplant ([100% = 36 lb N/ac, 70 lb P2O5/ac, 60 lb K2O/ac] and [125% = 45 lb N/ac, 88 P2O5/ac, 75 lb K2O/ac]) and at early squaring (74 lb N/ac and 93 lb N/ac for the 100% and 125%, respectively). The research was conducted in 2021 at the Lon Mann Cotton Research Station on a Memphis silt loam. Preliminary results show no difference in biomass accumulation between either the cultivars or fertilizer treatments. The research will be repeated in 2022 on silt loam and clay soils to determine if this trend is consistent across environments. [ABSTRACT FROM AUTHOR]

Seeking to fine-tune nitrogen (N) application, increase economic returns, and decrease environmental N loss, some Arkansas rice (Oryza sativa L.) producers are turning away from blanket N recommendations based on soil texture and cultivar and using Nitrogen Soil Test for Rice (N-STaR) to determine their field-specific N rates. In 2009, Roberts et al. correlated several years of direct steam distillation (DSD) results obtained from 18-in. soil samples to plot-scale N response trials across the state and developed a field-specific, soil-based N test for Arkansas rice. After extensive small-plot and fieldscale validation, N-STaR is available to Arkansas farmers for both silt loam and clay soils (using a 12-in. soil sample). To summarize the samples submitted to the N-STaR Soil Testing Lab in 2019, samples were categorized by county and soil texture. Samples were received from 61 fields across 16 Arkansas counties. Total samples received were from 8 clay and 53 silt loam fields. The N-STaR N-rate recommendations for these samples were compared to the producer's estimated N rate, the 2019 Recommended Nitrogen Rates and Distribution for Rice Cultivars in Arkansas, and the standard Arkansas N-rate recommendation of 150 lb N/ac for silt loam soils and 180 lb N/ac for clay soils. Each comparison was divided into 3 categories based on a decrease in recommendation, no change in recommended N rate, or an increase in the N rate recommendation. No significant differences were found when N-STaR recommended an increased N rate. Soil texture was a significant factor (P < 0.0001) when N-STaR proposed a decrease in the season total N rate when compared to the standard N rate. County was significant (P < 0.05) for decreased N rates when compared to the standard and producer's estimated comparisons suggesting that some areas of the state and specific soil series may have higher residual-N not accounted for by other current N-rate recommendation strategies. [ABSTRACT FROM AUTHOR]

Hybrid rice (Oryza sativa L.) has accounted for nearly 50% of Arkansas' total rice acres harvested during the last decade. Previous research conducted on the current recommendation of applying 30 lb nitrogen (N)/ac to hybrid rice cultivars at the late-boot growth stage indicated an increase in both grain and milling yields. The conclusions from previous research suggested that significant increases in grain and milling yields were due to the addition of a late-season N application; however, more research is needed to determine if the late-season N application is necessary due to inconsistent results. A study was initiated to examine grain and milling yields on hybrid rice when implementing a late-season N application across varying preflood N application rates. The RiceTec (RT) hybrids, RT Gemini 214 CL and RT XP753, were used in this study and are the most common hybrid rice cultivars grown in Arkansas. These two cultivars were planted at the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Arkansas, on a silt loam soil, and the Rohwer Research Station (RRS) near Rohwer, Arkansas on a clay soil. Results indicate that there is a positive impact from the late-season N application on both grain and milling yields from both cultivars at each of the locations. When lateseason N was applied, there was an increase of 11 to 16 bu./ac across the two locations. Also, the late-season N application resulted in a significant increase in head rice milling yield from 1% to 5% across both locations but showed no significant difference in total rice. When observing head rice yields from various plant components (main stem vs. tillers) within the same plots, there is a significant increase in head rice yield when applying the late-season N that is equal across both main steams and tillers. It is apparent that the late-season N application results in significant increases in both grain and milling yields. Further research is needed to better understand the relationship contributing to increased grain yield and milling yields when late-season N is applied to hybrid rice and define the physiological mechanism for this response and help predict when and where it will occur. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) deficiency in Arkansas soils is uncommon, but can negatively impact corn (Zea mays L.) growth and grain yield. Two fields (D2 and F4) in Fayetteville, Ark., were identified as sites for this study due to low soil-test Mg and relatively high potassium (K) to Mg ratios. The following treatments were applied preplant and incorporated into the seedbed: untreated check, 30, 60, and 90 lb Mg/acre; 24 lb S/acre; 45, 90, and 135 lb K2O/acre. In addition, all plots received 30 lb N/acre preplant and 200 lb N/acre between the V6 and V8 growth stages. Whole-plant aboveground biomass samples were collected at the V6 growth stage and ear-leaf samples were collected at the R1 growth stage. No significant difference was measured in grain yield (P = 0.9534) in D2; however, a significant difference in grain yield was measured in F4 (P < 0.0001). Corn in F4 exhibited significant differences in K concentrations in the tissue at both the V6 (P = 0.0114) and R1 (P = 0.0162) growth stages. Corn in the D2 field exhibited significant differences in Mg concentration at the V6 (P < 0.0001) and R1 (P = 0.0144) growth stages. These results suggest that the interactions of Mg and K within the soil are not well understood and further research is needed to predict corn responses to Mg fertilization. [ABSTRACT FROM AUTHOR]

The popularity of cover crops within Arkansas continues to increase, and more producers are implementing them into their corn and soybean rotations. A need for Arkansas-specific data on the effects of long-term no-till and cover crop implementation on corn performance will be essential. A study was established to determine the effects of various winter cover crop treatments on corn stand establishment and grain yield. Cover crop treatments included a winter fallow, a cereal rye every year, an Austrian winter pea every year, an alternating cover crop where a cereal was planted prior to soybean, and a legume was planted prior to corn, and a cover crop species blend based on the soil health recommendation (blend of cereals and legumes). During the 2020 growing season, there were no significant differences in corn plant population across all cover crop treatments. The data for stand establishment was highly variable across treatments and related to surface residue at planting, with higher surface residue leading to lower plant populations. Corn grain yield was significantly influenced by winter cover crop treatment (P < 0.001), with the winter fallow resulting in the lowest overall yield (82 bu./ac) and the alternating cover crop resulting in the highest (159 bu./ac). The yield data are not supported by the corn plant population data as the highest corn plant population resulted in the lowest overall corn grain yield. These results suggest that the implementation of cover crops into corn production systems is more complex than for other crops such as soybean. There is still much to be learned regarding the complex interaction of cover crop biomass production and the resulting impacts on corn productivity and soil health. [ABSTRACT FROM AUTHOR]

Little is known about the effects of soybean (Glycine max L.) management practices on the subsequent rice (Oryza sativa L.) crop's success. This study was continued to determine rice response to different soybean maturity groups (MGs) and planting dates when grown in rotation with rice on a silt loam soil in Arkansas. Various soybean planting dates (optimum and late) and MGs (3.5, 4.7, 5.4, and 5.6) were considered followed with a single cultivar of rice. The rice was measured for the total N uptake (TNU) at 50% heading, grain yield and N fertilizer rate needed to achieve 95% relative grain yield (RGY). Total N uptake was effected by the previous soybean planting date, with significantly higher rice N uptake following a late-planted soybean crop. The interaction of planting date by MG of the previous soybean crop influenced the maximal grain yield achieved by the rice crop (P < 0.0001) and the N rate needed to achieve 95% RGY (P = 0.0007). Management techniques should be considered when implementing a soybean-rice rotation on a silt loam soil in Arkansas to maximize rice grain yield and overall farm profitability through minimizing fertilizer-N needed to achieve high grain yields. [ABSTRACT FROM AUTHOR]

The cost of nitrogen (N) fertilization for a rice (Oryza sativa) producer is a determining factor in the profit returned from a rice crop. In 2016, 68% of the rice grown in Arkansas was grown in rotation with soybean (Glycine max), the leading crop in both profit and acres harvested in the state (Hardke, 2017). Variety selection and management of the soybean crop may influence soil-N credits returned to the soil and ultimately the N rate needed to maximize yield in the successive rice crop. A rice crop's performance and input cost is strongly related to the plant-available N. The potential to reduce the amount of N fertilizer required by the rice through management of the previous soybean crop could provide savings with no additional input cost to a rice producer. The total N uptake (TNU), yield, and soil-N credits developed were measured in four maturity groups (MGs) of soybean. A single cultivar of rice followed all four MGs to compare the rice TNU and yield between previous MGs and N rate applied as a single pre-flood treatment of urea. The results from the 2016 soybean crop and 2017 rice crop show no significant difference between soybean MG grown and rice yield (P = 0.9502). There was no significant difference (P = 0.8067) in plant-available N between previous MGs the following spring, nor was there a significant difference between previous MG and rice total N uptake (P = 0.9677). The preliminary data suggest MG of soybean alone does not have an impact on a following rice crop's success under the conditions of this initial year's study. Further research will be conducted to evaluate the impact of soybean planting date on a following rice crop. [ABSTRACT FROM AUTHOR]