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Sandy soil is typically poor in organic matter. When areas with sandy soil are used for pasture prior to soybean cultivation, the availability of nitrogen (N) for plants is limited even further. Our objective was to evaluate if inoculation combined with N fertilization increases N content in the soil and N supply to soybean plants in post-pasture and post-soybean areas. Four experiments were conducted in degraded post-pasture and post-soybean areas in a sandy soil (Rhodustult), between 2016 and 2018, in Brazil. Treatments used a combination of inoculant (zero, 4, 8 and 12 rates ha−1) and mineral N (0, 25, 50, and 100 kg ha−1) with four replicates. It was using the soybean cultivar TMG 7062 IPRO. The post-soybean area had higher N content in the soil than the post-pasture area; 33, 32, and 21% for total N, microbial biomass nitrogen (MBN), and inorganic nitrogen (IN), respectively. Soybean shoots from the post-soybean area also had greater accumulations of N (86 kg ha−1 of N). Increased N fertilization linearly raised levels of N in the soil (total N, MBN, and IN). In both areas, the effect of inoculation was restricted by the increase of total N in the soil. Inoculation combined with moderate rates of N in soybeans (50 kg ha−1) increased levels of N in the soil and N supply to plants in post-pasture areas. In post-soybean areas, inoculation alone fulfilled the N soybean need. [ABSTRACT FROM AUTHOR]

Biochar used in this study was prepared from wheat straw and enriched with 10% solutions of chemically pure salts: ammonium sulfate [(NH4)2SO4] and magnesium sulfate (MgSO4 7H2O). The aim of this study was to determine the growth response of Perennial ryegrass L. as well as identify changes in chemical and biological properties of sandy soil after the application of biochar. A significant increase in the amount of Perennial ryegrass L. biomass was determined after amending the soil with unenriched biochar and biochar enriched with (NH4)2SO4. The highest immobilization of available forms of Mg was observed for biochar enriched with (NH4)2SO4. The highest dehydrogenase activity was determined in the soil with biochar enriched with MgSO4 7H2O. [ABSTRACT FROM AUTHOR]

This study was undertaken to study the impact of adding <75 μm elemental sulfur (ES) on P availability from a range of <250 μm ground rock phosphates (RP) namely; Minjingu (Mi) from Tanzania, Khouribga from Morocco (Mo) and Duchess (D) from Australia. Italian ryegrass (Lolium multiflorum, Thumpa tetraploid) grown in a glasshouse was used as the test crop and tops were harvested 5 times over 27 weeks. Co-granulating RP and 10.7% ES yielded 30–70% more ryegrass tops than RP alone, with the greatest effect with Mi. Fertilizer P recovery in the tops from the RP was 5.2% with D and 6.5% and 7.8% from Mi and Mo, respectively. ES addition increased this by 51% from Mo, 98% from D and 194% from Mi. Co-granulation of RP with ES has been shown to be an effective means of releasing plant available P to crops from RP with minimal fertilizer processing. [ABSTRACT FROM AUTHOR]

Asexual fungusNeotyphodiumspp. are often associated with aboveground parts of different grasses. Perennial ryegrass (Lolium perenneL.), dominant cool-season grass species in New Zealand, is frequently infected by endophytic fungus (Neotyphodium lolli). To evaluate the growth, nutrient status, and avoidance to dehydration stress, clones of diploid perennial ryegrass either infected withNeotyphodium loliiAR29 endophyte (E+) or not infected (E−) were grown in a potted Andisol with intermittent wetting-drying cycles in a controlled growth chamber. Results showed that endophyte infection (E+) significantly reduced plant height, tiller number, shoot and root dry weights, and root volume with an associated increase in root/shoot ratios of ryegrass. The E+ plants showed a greater shoot and lower root avoidance to dehydration stress than the E− plants. The negative values of relative interaction intensity index between the diploid ryegrass and AR29 endophyte association suggested that these host-endophyte associations were parasitic under intermittent soil wetting-drying cycles. While the nitrogen (N) and phosphorus (P) concentration, plant production index, and water-use efficiency were significantly greater in E+ plant than in E− plants, the N and P efficiency ratios were greater in E− plants than in E+ plants. Results suggested that the endophyte mediation may have synergistic or antagonistic effects which depend on particular host genotype-endophyte combinations and environmental conditions to promote drought tolerance in grasses for degraded land restoration or forage production. [ABSTRACT FROM AUTHOR]

Removal of soil phosphorus (P) in crop harvest is a remediation option for soils high in P. This 4-year field-plot study determined P uptake by annual ryegrass (ARG,Lolium multiflorumLam.) and common bermudagrass (CB,Cynodon dactylon(L.) Pers.) from Ruston soil (fine-loamy, siliceous, thermic Typic Paleudult) enriched in P by five previous annual applications of poultry litter, and related P removed to Bray 2 P in surface (0–15 cm) soil. Decreases in surface soil Bray 2 P were largely attributable to uptake. Phosphorus uptake was positively related to Bray 2 P but approached a limit. Mass of P removed in harvest closely approximated the decrease in mass of surface soil Bray 2 P. Maximum Bray 2 P drawdown per harvest (ARG and CB, average) was ˜3 mg kg−1at Bray 2 P ˜ 300 mg kg−1, generally consistent with measured decreases in Bray 2 P. [ABSTRACT FROM AUTHOR]

A pot scale trial investigated the agronomic performance of two organomineral fertilizers (OMF15—15:4:4 and OMF10—10:4:4) in comparison with urea and biosolids granules to establish ryegrass (Lolium perenneL.). Two soils of contrasting characteristics and nitrogen (N) application rates in the range of 0–300 kg ha−1were used over a period of 3 years. Fertilizer effects were determined on: (1) dry matter yield (DMY) and crop responses, (2) nitrogen use efficiency (NUE), and (3) selected soil chemical properties. Ryegrass responded linearly (R2≥ 0.75;P< 0.001) to organomineral fertilizers (OMF) application increasing DMY by 2–27% compared with biosolids but to a lesser extent than urea (range: 17–55%). NUE was related to concentration of readily available N in the fertilizer: urea and OMF showed significantly (P< 0.05) greater N recoveries than biosolids. Total N in soil and soil organic matter showed increments (P< 0.05), which depended on the organic-N content in the fertilizer applied. Soil extractable P levels remained close to constant after 3 years of continuous OMF application but increased with biosolids and decreased with urea, respectively (P< 0.05). The application of biosolids changed soil P Index from 5 to 6; hence, there is a need to monitor soil P status. Both OMF10and OMF15formulations are suitable for application in ryegrass. [ABSTRACT FROM AUTHOR]

Poultry-litter applications to pastures can result in relatively high soil phosphorus (P) levels, which in turn can contaminate runoff and degrade surface water quality. New management protocols for temperate grasslands are needed to reduce the risk of P transport to surface water. The effects of three land-use treatments on soil characteristics related to P runoff were investigated using small watersheds with 8% slope near Booneville, Arkansas, U.S. The land use treatments were (1) haying of bermudagrass overseeded with winter annual forage (ryegrass or rye), (2) rotationally grazed, and (3) rotationally grazed with 12-m-wide tree buffer on the downhill portion of the plot. Plots and trees were established in 2003. Annual spring application of poultry litter (5.6 Mg ha−1) to the hayed or grazed portions of the plots was started in 2004. Grazing treatments were imposed shortly thereafter. By the summer of 2008 (4 years of treatments), soil concentrations of Bray 1–extractable P and soluble reactive P had increased significantly from approximately 40 and 4 mg P kg−1 soil, respectively, to more than 200 and 30 mg P kg−1 soil, respectively, in the areas of the plots receiving poultry litter. Soil bulk density in the portions of the plots being grazed had increased significantly also. The soil collected from the forested riparian buffer in 2008 had similar soil bulk densities and Bray 1–extractable P concentrations as the plots did in 2003 before treatments were imposed. [ABSTRACT FROM AUTHOR]

Most soils in Florida are very sandy, and water-soluble fertilizers (WSF) are subjected to leaching loss. Alternate fertilization is a promising practice to reduce such loss. Dolomite phosphate rock (DPR), which contains calcium, magnesium, and phosphorus, is potentially useful for agricultural production and landscaping plants. In this study, DPR fertilizers were developed from mixing of DPR material and N-viro soil. A typical agricultural soil (Alfisol) in Florida was used for greenhouse studies, and ryegrass and citrus seedlings were tested. The DPR fertilizers appeared superior to WSF for the growth of ryegrass based on dry-matter yield and nutrient concentrations in plant; however, it was not evident in citrus seedlings. DPR fertilizers were effective in raising pH (by 3 units) and electrical conductivity of acidic sandy soils and increasing soil organic matter, total nutrients, and available nutrients. The concentrations of copper, lead, and zinc in the plant tissues were less than toxicity limits. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is both a macronutrient for plants and an effective amendment to reduce lead (Pb) toxicity in soil. Thus, in Pb-polluted soil with low P availability, P will act as a nutrient as well as a Pb-immobilizing agent. However, this has not been fully investigated. A soil with 2.50 mg kg−1 Olsen P was spiked with soluble Pb and then amended with superphosphate to examine the effect of P on soil Pb availability and ryegrass (Lolium perenne L. cv. Aubisque) growth. It was found that P/Pb = 2 increased ryegrass yield by 804% and decreased root Pb concentration and soil diethylenetriaminepentaacetic acid (DTPA)–extractable Pb concentration by 25.6% and 1.0%, respectively. As P amendment increased to P/Pb = 4, both plant yield and root Pb concentration declined compared with P/Pb = 2. Results of the sequential extraction indicated that the proportion of carbonate phase Pb decreased, while that of the manganese oxide phase increased as P was added. The proportion of residual Pb was little affected by the amendment. The results suggest that in soils with low P availability and high Pb availability, availability of soil Pb and root concentration of Pb are less affected, whereas the toxicity of Pb is greatly depressed by the P amendment; P/Pb = 2 is high enough to alleviate the stresses of low P availability. [ABSTRACT FROM PUBLISHER]

To examine the possibility of managing manganese (Mn) deficiency through mixed cropping, berseem was grown as a monoculture and in mixed cropping with oats, ryegrass, or raya in a Mn-deficient soil under screen-house conditions. In no-Mn berseem monoculture treatment, shoot dry weight (SDW) and root length (RL) were, respectively, 33% and 45% of the maximum recorded values obtained with berseem grown in mixed cropping with ryegrass at 60 days of growth. Corresponding values of SDW and RL of berseem when grown with raya were 78% and 76% of the maximum, respectively. Even though berseem grown in mixed cropping with ryegrass and raya had smaller RL/SDW ratio and greater shoot growth rate than berseem grown as monoculture, it acquired a high shoot Mn concentration because of 3.8 times more Mn influx. A high Mn influx was the result of a high concentration gradient that developed because of depletion of Mn at the root surface. [ABSTRACT FROM AUTHOR]

Nutrient accumulation characteristics and mineral content of plants depend on several factors such as crop and site characteristics, environmental conditions, and soil nutrient levels. Nutrient interactions are rather complex and may have an important role in this context. It is evident that phosphorus (P)–potassium (K) interaction is a part of cation–anion balance in plants. Although several authors demostrated the positive P-K interaction in plants, results are still inadequate. Studies on P-K interaction and adequate P/K ratios are needed to improve nutrient efficiency. Pot experiments were carried out under greenhouse conditions with perennial ryegrass (Lolium perenne L.) grown in three soils different in texture, soil organic matter (OM), pH, and available nutrient levels: an Eutric cambisol, a Calcaric fluvisol, and a Haplic phaeosem. Soil samples were taken from selected plots of National Long-Term Fertilization Trials (NLFT) after 30 years of fertilization. Besides the unfertilized control, increasing rates of P were applied in four replicates at four levels of P supply resulting from long-term P fertilization. Dry-matter (DM) production, P and K accumulation characteristics, nutrient concentrations, and K/P ratios of perennial ryegrass were studied for 4 months by taking four cuts. From the results, it was evident that both P and K accumulation of plants were closely related to DM accumulation. Phosphorus accumulation characteristics and amounts of P taken up by plants responded both to the level of long-term P supply and to rates of freshly applied P. Better levels of P supply had a beneficial influence on K uptake and K concentrations in plants. Phosphorus concentrations ranged between 0.20% and 0.53% P, whereas concentrations of K were between 1.63% and 5.64%. As the interaction between P and K may influence that of other nutrients, further research is needed to identify these relationships. [ABSTRACT FROM PUBLISHER]

The effects of nitrogen (N), phosphorus (P), and zinc (Zn) fertilization on the yield of ryegrass was studied in a greenhouse experiment. The treatment combination was set according to the Box-Wilson method. By performing multiple regression analysis, the yield was described as a function of fertilizer doses by a polynomial of the second degree. The R2 value of the regression was 0.863. Based on the regression equation, we calculated the optimal fertilizer doses and evaluated the effects of fertilizers by means of three-dimensional graphs. According to the graphs, it can be stated that the yield-increasing effect of N is dominant, but P and Zn doses also influenced yield. The optimum concentrations of the doses were N, 120; P2O5, 89; and Zn, 2.8 mg kg-1. Optimal dry matter (12-14 g pot-1) can be produced with a large range of Zn and P concentrations and a relatively large N range. At doses more than the optimal dose for each element, a slight depression can be observed. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted in two acidic soils (pH 4.8) with similar properties except for phosphorus (P) status to investigate the influence of different P fertilizers [Kunyang phosphate rock (KPR), monocalcium phosphate (MCP)] on ryegrass growth and different soil P fractions in the two soils. The P treatments were KPR at 50, 100, and 250 mg P kg-1 and MCP at 50 mg P kg-1. Results showed that the application of P fertilizers produced significant increase of ryegrass growth compared with no P application on soil with low P status. Dry weight of ryegrass did not increase after P application, compared with no P application on soil with high P status. Through P fractionation as modified method of Hedley, Stewart, and Chauhan (1982), inorganic resin P, sodium bicarbonate (NaHCO3) P, and sodium hydroxide (NaOH) P increased after MCP treatment compared with no P application. The PR application only increased resin P and hydrochloric acid (HCl) P. Soil organic P fractions were stable and less affected by P application. The average of KPR P dissolved in the two soils across all P rates was low: only about 19% of the averaged amount of KPR P applied, which was due to its low reactivity. This explains the poor agronomic effectiveness of KPR with respect to MCP. [ABSTRACT FROM AUTHOR]

The supply of nutrients to plants from organic growing media depends on mineralization as the addition of inorganic nutrients is forbidden in certified organic systems. The objective of this study was to determine the relationship between total phosphorus (P), extractable (Olsen's) P, organic P, and biomass P in growing media and uptake of P by ryegrass. Three proprietary products were used alone and combined in 1:2 and 2:1 proportions to give nine growing media. Perennial ryegrass (Lolium perenne L. cv. 'Choice') was irrigated with a modified Hoagland's solution minus P, and the shoots were harvested after 28, 56, and 84 days. There was no significant correlation between the amounts of the different forms of P in the growing media and ryegrass dry weight or P concentration in harvested grass. However, total ryegrass P uptake was significantly positively correlated with initial total P and organic P in the growing media. [ABSTRACT FROM AUTHOR]

The relationships between potential laboratory indices for plant-available nitrogen (N) and the plant N uptake in a pot experiment with ryegrass were assessed for 13 mineral soils and 2 peat soils. The methods included aerobic soil incubation, soil incubation in a bioreactor, hot potassium chloride (KCl)-extractable mineral N, 0.01 M calcium chloride (CaCl2)-extractable N, and N loss at heating. The indices for total plant-available N accounted for 63-93% of the variance in N uptake in a statistical analysis with all soils (n = 15) and 27-89% for the mineral soils (n = 13). Most indices were not a direct quantitative measure of the plant N uptake. The N mineralization indices accounted for 57-86% of the variance in N mineralization for all soils and 5-50% for the mineral soils. Hot KCl-extractable mineral N and 0.01 M CaCl2-extractable N were the most promising rapid indices for plant-available N. [ABSTRACT FROM AUTHOR]

Understanding differences in the phytoavailability of various phosphorus (P) sources should improve matching P additions to plant needs and minimize excessive buildup of bioavailable P, which can degrade aquatic systems. We evaluated relative P phytoavailability (RPP) of different P sources in glasshouse and field studies. Bahiagrass (Paspalum notatum Fluggae), ryegrass (Lolium perenne L.), and a second bahiagrass crop were grown in succession in a P-deficient soil amended with four sources of P (triple superphosphate (TSP), Boca Raton and Pompano; biosolids, and poultry manure), each applied at two rates in the glasshouse study and to an established bahiagrass pasture in the field. The RPP values estimated from plant P uptake of each organic source of P relative to TSP in the glasshouse were similar for the three croppings and similar to the estimates derived from the field study, but varied for the different P sources. Values ranged from 30% for poultry manure to 85% for Boca Raton biosolids. Boca Raton biosolid P was as readily available as P in TSP and would be classified as a high RPP (>75% RPP) source, but Pompano biosolids and manure would be classified as moderate RPP materials (25-75% RPP). The RPP values observed in manure and Pompano biosolid treatments are consistent with 50% “effectiveness” suggested for biosolid P in U.S. Environmental Protection Agency (USEPA) guidelines, whereas P bioavailability of Boca Raton biosolids is similar to mineral fertilizer. [ABSTRACT FROM AUTHOR]

The effectiveness of intensively milled gneiss and potassium (K-feldspar) as K fertilizers was evaluated through a glasshouse experiment with ryegrass. Plant were grown on two soil types for 12 months. Results show that the agronomic effectiveness of milled gneiss was nearly as great as potassium sulfate (K2SO4), but milled K-feldspar was much less effective because of the relatively small extent of dissolution of K-feldspar in the soil. The positive effects of K-silicate rock fertilizers (K-SRFs) included increases in plant biomass, uptake of K and silicon (Si), and soil pH with increasing application rate of the K-SRFs. The application of K-SRFs will be most advantageous for amending K-deficient soils, and high-energy milling provides a simple method for manufacturing effective multinutrient SRFs. [ABSTRACT FROM AUTHOR]

An irrigated field trial was conducted to test the effects of white clover in three turfgrass species (perennial ryegrass, Kentucky bluegrass, and creeping bentgrass) on color, clipping yield, and botanical composition and to estimate nitrogen (N)2 fixation and N transfer from white clover to associated turfgrass species under different N-fertilization conditions in 1999-2002. Nitrogen fertilizers significantly increased color ratings in all observations. Grass-white clover mixtures had better color ratings than pure grass at all sampling dates and seasonal averages in unfertilized conditions. Fertilized pure grass plots yielded significantly more than control plots in all turfgrass species. Nitrogen fertilization did not affect clipping yield greatly in turfgrass-white clover mixtures. Nitrogen application significantly decreased white clover percentage in the harvested clippings in second and third year. Nitrogen fertilization increased tissue N concentration positively in all turfgrass species grown alone. In contrast, N fertilization did not greatly affect tissue N concentration of either turfgrass species or white clover in the mixtures. Nitrogen fixation of white clover was estimated as 24.6, 30.7, and 33.8 g m-2 year-1 in perennial ryegrass, Kentucky bluegrass, and creeping bentgrass, respectively. The total estimated N2 fixation gradually decreased with increasing N fertilization. Nitrogen transfer from white clover to the associated turfgrass varied from 4.2 to 13.7% of the total N that the white clover fixed annually. [ABSTRACT FROM AUTHOR]

The aim of study was to find the correlation between the concentration of the total amount of heavy metals of soils and that of plants because it shows which elements can be accumulated by different plants. The transfer coefficient is the metal concentration in plant tissues aboveground divided by the total metal concentration of soil. Pot experiments were conducted under greenhouse conditions. The total lead (Pb) content (about 21 mg · kg-1 soil) of soils was higher than the cadmium (Cd) content (about 0.21 mg · kg-1 soil). The Cd concentration of lettuce (averaging 0.93 mg · kg-1) was higher than that of ryegrass (averaging 0.20 mg · kg-1). The transfer coefficient of Cd was lower in ryegrass (averaging 0.95) than in lettuce (4.47). In this experiment, the concentration of Cd was almost five times higher in the four‐leaf lettuce than the Cd content of soil. The transfer coefficient of Pb was generally 0.064 in both plants. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate whether an insoluble polyacrylate polymer could be used to remediate a sandy soil contaminated with cadmium (Cd) (30 and 60 mg Cd kg -1 of soil), nickel (Ni) (50 and 100 mg Ni kg -1 of soil), zinc (Zn) (250 and 400 mg Zn kg -1 of soil), or the three elements together (30 mg Cd, 50 mg Ni, and 250 mg Zn kg -1 of soil). Growth of perennial ryegrass was stimulated in the polymer‐amended soil contaminated with the greatest amounts of Ni or Zn, and when the three metals were present, compared with the unamended soil with the same levels of contamination. Shoots of plants cultivated in the amended soil had concentrations of the metals that were 24–67% of those in plants from the unamended contaminated soil. After ryegrass had been growing for 87 days, the amounts of water‐extractable metals present in the amended soil varied from 8 to 53% of those in the unamended soil. The results are consistent with soil remediation being achieved through removal of the metals from soil solution. [ABSTRACT FROM AUTHOR]

It was hypothesized that supplying potassium (K) in concentrated complex fertilizer (CCF) form with nitrogen (N) (NK CCF) to all fertilizer microsites, rather than in NK-blended fertilizer form to a fraction of the total fertilizer microsites, should enhance the rate of K uptake by perennial ryegrass. Two complementary pot experiments were conducted to test this hypothesis. The results demonstrated that plants fertilized with an NK CCF absorbed K at faster rates than those fertilized with an NK blend and that use of K2SO4 in place of KCl as the K source lowered the rate of K uptake by plants regardless of fertilizer form. Form of fertilizer (i.e., CCF or blend), however, had no effect on NH4+ or NO3- uptake. Unfortunately, the positive effects of the CCF on K absorption were only manifest during the second 2 weeks of regrowth and did not result in significant improvements in dry matter production by the end of the 5-week regrowth periods. [ABSTRACT FROM AUTHOR]

The recovery of 15N-labelled nitrogen (N) by perennial ryegrass can be significantly increased by mixing gypsum (CaSO4 · 2H2O) into soil rooting medium at rates equivalent to 0.7 t ha -1. Similar improvements in fertilizer N efficiency might be achieved, at less cost and more conveniently, by applying smaller amounts of CaSO4 anhydrite more strategically to fertilizer microsites as a fertilizer filler or diluting agent, in calcium ammonium nitrate (CAN), in place of CaCO3. With this in mind, two complementary pot experiments were conducted under simulated spring conditions in a controlled environment chamber. Use of CaSO4 as diluting agent, in place of CaCO3, appreciably enhanced (>30%) the uptake of labeled N by perennial ryegrass plants within the second week of regrowth, but thereafter, because losses of 15N-labeled NO3--N from pots by denitrification or leaching had been minimal, plants in both treatments eventually recovered equal amounts of this N form from the soil. [ABSTRACT FROM AUTHOR]

Short chain organic acids (C[sub 2] to C[sub 5]), toxic for paddy rice, can be produced in flooded soils treated with organic residues. In order to study the liberation of organic acids into the solution of a flooded soil treated with residues of a ryegrass crop, an experiment was carded out in the greenhouse. The trial was planned in random blocks with three replicates using the following treatments: (a) without ryegrass residues, (b) ryegrass residues kept on the soil surface, and (c) ryegrass residues incorporated into the soil. The organic acids acetic, propionic, butyric, isobutyric, valeric, and isovaleric, were evaluated during eight weeks by gas chromatography. Results showed that the use of ryegrass residues increases the organic acids concentration in the soil solution. The highest concentrations were obtained at 10cm deep with incorporated ryegrass. However, the organic acid concentration at 2 cm deep with ryegrass kept on the surface was equally high, probably at toxic levels for paddy rice. Acetic acid was the one presented at the highest concentration in the soil solution for all treatments. [ABSTRACT FROM AUTHOR]

Near infrared reflectance spectroscopy (NIRS) was tested as a method of predicting potentially mineralizable N (PMN) in organic potting mixes. Initially, calibration models were developed using the near infrared spectra of 100 potting mix formulations and the amount of N recovered by ryegrass herbage after 168 d of growth in the formulations, focusing on which combination of a range of regression, derivatization and scatter correction techniques gave the best calibration model. In the second part of the study, a validation exercise was performed, where the 100 formulations were split into separate calibration and validation sets. In the initial calibration exercise, the most effective combination of regression technique and spectral pretreatments was modified partial least squares in conjunction with a second order derivative and a standard normal variate and detrend scatter correction technique, which had an R[SUP2] of 0.99. However, in the validation study the coefficient of determination was much lower (r[SUP2] = 0.73), and results were not in line with expectations. The explanation offered for the poor validation results relates to the constriction of the set of calibration samples. Nevertheless, NIRS appears to have great potential for predicting the performance of organic potting mixes, and despite several practical drawbacks is worthy of investigation by other workers. [ABSTRACT FROM AUTHOR]