Leaf mineral element concentrations and growth of sweet sorghum subjected to acid soil stress

Abstract

The nutritional profile of sweet sorghum [Sorghum bicolor (L.) Moench] cultivars grown under acid soil field stress conditions is a critical consideration when developing plants which are adapted to these infertile soils. Uptake and accumulation of macro‐ and micronutrients vary among genotypes and ultimately Influence plant growth and development. This study compared fourteen sweet sorghum germplasm lines and varieties for their Individual patterns of leaf nutrient concentrations and productivity when grown under acid soil field conditions (pH 4.45 to pH 4.85) at three locations over a two‐year period. Significant year x location interactions were found for Fe, K, and Ca concentrations at both Blairsville and Calhoun and for Mn and P levels at Blairsville and Calhoun, respectively. Data from Calhoun on plant height, dry weight, visual stress ratings, and rainfall indicate a possible association between drought tolerance and acid soil tolerance in sorghum. No significant differences in A1 concentrations were found among these sweet sorghum lines and varieties, which indicate that their acid soil tolerance mechanisms are probably not related to A1. MN 1054 accumulated the highest levels of Mn in the three acid soils. The highest concentrations of Mg and P were found in Brandes. MN 960 had the highest visual stress ratings (highest susceptibility) while Brandes, Ramada, Roma, and Wray were the most tolerant. All fourteen cultivars apparently have some tolerance to acid soil stress conditions.     

Growth and nutrient interrelationships of three vegetable crops with different sensitivities to soil pH as affected by lime and fertilizer treatments

Abstract

In seeking reasons for differences in sensitivity among vegetables to low soil pH and the roles of lime and fertilizers, an experiment was conducted in 1984 with 3 crops: snapbeans (Phaseolus vulgaris L.), tomatoes (Lycopersicon esculentum L.), and red beets (Beta vulgaris L.). The lime treatments, check, calcitic lime, and dolomitic lime, were applied in 1979 and resulted in soil pH levels of 5.5, 6.9 and 6.7, respectively, at the time of planting. Banded fertilizer treatments were randomized in each lime plot. These were: check, NP, N, NPK, NPCa, and NPMg for snapbeans while with tomatoes and beets, K was added to the N, NPCa and NPMg treatments. Leaf samples from each plot were analyzed for 11 elements.

Growth responses of the 3 crops were related to the plant sensitivity to acid soils. When grown on soil with pH 5.5, snapbean vine weights and pod yields were not affected, tomato yields tended to be lower, and red beet yields were substantially reduced. Leaf Mn levels increased with the greater sensitivity to acid soils. Both calcitic and dolomitic limes had little effect on snapbean yields, moderate effects on tomato yields, and more than doubled yields of red beets. Lime types affected primarily leaf Ca and Mg. The NPK fertilizer treatment increased yields of tomatoes and red beets but increased only vine weights of snapbeans. Leaf Mn was increased substantially in the NPK treatment. When gypsum or Epsom salts was added, yields were not affected.

The sensitivity of red beets and to a lesser extent tomatoes could not be explained on the basis of manganese toxicity or poor uptake of calcium or magnesium. The results did suggest that poor phosphorus uptake could be a primary cause.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.     

Incinerated Sewage Sludge Products as Amendments for Agricultural Soils: Leaching and Plant Uptake of Trace Elements

Preliminary leaching column and greenhouse plant uptake studies were conducted in two soils with contrasting characteristics amended with varying rates (0 to 148.3 Mg ha^?1) of incinerated sewage sludge (ISS) and weathered sewage sludge (WISS) to estimate the leaching losses of trace elements from the soils amended with incinerated sewage sludge by products and to evaluate the uptake and accumulation of these elements in various parts of Sorghum vulgaris var. sudanense Hitche. (“Sorgrass''), a Sorghum-Sudan grass hybrid. Results of this study indicated that leaching of Cr, Cd, Zn, Cu, Ni, Fe and Mn from soils amended with ISS and WISS increased with increasing rates of amendment. Results of the leaching column study further revealed greater leaching losses from coarse-textured soil compared to medium-textured soil and also from ISS amended soils than with WISS amended soils. Results further suggested that the type of element and the interaction between the element and soil properties affected the leachability of various trace elements. The uptake study indicated uptake and accumulation of trace elements by plant parts increased with increasing rates of amendments. Greater plant uptake and accumulation of trace elements were observed in plant parts grown in soils amended with ISS compared to that of WISS. Results also indicated a greater accumulation of trace elements in below ground part of the plants (roots) compared to that was observed in above ground parts (shoots). Limited data obtained from this one season preliminary studies demonstrated that incinerated sewage sludge products from wastewater treatment plants could be used as soil amendments at low application (no more than 24.7 Mg ha^?1) for optimum plant growth, and dry matter yield without resulting in substantial accumulation of metals in plant parts at concentrations above the recommended critical limits and without causing significant leaching losses of various trace elements. It is imperative that long-term field studies are necessary to evaluate the long-term impact of using these new products in leaching and accumulation of various trace elements in plants and soils.     

Effect of zeolite and phosphogypsum on yield,plant uptake,and content of strontium in soil

Abstract

Natural zeolite (clinoptilolite containing tuff) can be used as an adsorbent of strontium (Sr) from phosphogypsum when applied as a solonetzic soil amendment. This study investigated the influence of the zeolite on biological yield, content of water‐soluble Sr in soil, its availability, and plant uptake. A field experiment was conducted from 1993 to 1995 in the Volgogradskaya region of Russia. Two methods of phosphogypsum and zeolite application were used: “separate” and “as a mixture” (10 tons ha^‐1 of phosphogypsum and 0.5 ton ha^‐1 of zeolite in both cases). After the application of the amendments, barley (Hordeum vulgare) and grass sorghum (Sorghum sudanensis) were grown on the ameliorated sites in 1994 and 1995, respectively. Our results suggest that zeolite, being applied with phosphogypsum as a mixture, decreased by 15 to 75% the content of water‐soluble Sr in the soil, minimizing the risk of soil pollution. The uptake of Sr by plants depended on the biological character of the crop grown. Barley was found to be a “strong‐anticoncentrative” type of plant. However, grass sorghum was found to be more sensitive to the rise of Sr content in the soil. The highest biomass production of barley and grass sorghum was obtained with the application of zeolite and zeolite plus phosphogypsum. Plants grown on a single phosphogypsum‐treated sites had a declining tendency in biological yield. Our results suggest a positive influence of zeolite applied with phosphogypsum for the amelioration of solonetzic soils on the growth and uptake of Sr by plants.     

Effect of sewage sludge application to amelio‐rate iron deficiency of grain sorghum

Abstract

Recent research has indicated that land application of municipal sewage sludge to calcareous soils can be used to ameliorate iron (Fe) deficiency of grain sorghum [Sorghum bicolor (L.) Monech]. A greenhouse study was conducted to determine the response of grain sorghum grown on three different soils to application of sewage sludge. Sludge applied at rates of 0, 7.5, 15.0, and 25.0 g/kg soil did not completely ameliorate grain sorghum Fe deficiency. When FeEDDHA was soil applied, sewage sludge application significantly increased plant growth due to increases in soil phosphorus (P) availability. Application of sewage sludge at rates greater than 7.5 g/kg reduced dry matter production of grain sorghum in the FeEDDHA amended Orelia SC soil, the soil with the lowest total neutralizing potential. The decreases yield was possibly due to toxic levels of soil and plant copper (Cu) and zinc (Zn), and increased soil salinity.     

Tillage and Forage System Effects on Forage Yields and Nutrient Uptake under Broiler Litter–Amended Soils

Abstract

Planting and harvesting high‐yielding forage grasses may remove phosphorus (P), copper (Cu), and zinc (Zn) from surface soils with a long history of broiler litter application. A study was conducted in Alabama's Sand Mountain region from 1998 to 2000 to determine tillage and forage systems best suited for removing nutrients from such overloaded soils. Tillage treatments included no‐till, moldboard plowing, chisel plowing, and each combined with paraplowing. Forage treatments included bermudagrass (Cynodon dactylon (L.) Pers.) cv. Russell, tall fescue (Festuca arundinacea Schreb.) cv. Kentucky‐31, and an annual rotation of ryegrass (Lolium multiflorum Lam.) and sorghum sudangrass (Sorghum bicolor L. Moench×Sorghum vulgare sudanense). The annual rotation produced highest yields and P uptake. Moldboard plowing the annual rotation further increased yields. It appears the annual rotation best removes P, Cu, and Zn via plant uptake. Tillage reduced P concentrations in the soil surface in the following order: moldboard>chisel>no‐till.     

Effect of biochar application on mineral and microbial properties of soils growing different plant species

Biochar is widely used as a soil amendment to increase crop yields. However, the details of its impact on soil properties have not been fully understood. A pot experiment was conducted using soybean (Glycine max (L.) Merr. cv. Toyoharuka) and sorghum (Sorghum bicolor (L.) Moench cv. Hybrid Sorgo) under four soil treatment combinations (cattle farmyard manure with or without biochar and rapeseed cake with or without biochar) to elucidate the mechanisms of its beneficial effects on plant growth in terms of the microbial community structure and mineral availability in soils with different types of organic manure application. The application of biochar significantly increased the growth of both species, particularly sorghum with rapeseed cake application by 1.48 times higher than that without biochar. Microbial activity in soil was also enhanced by biochar application in both species with rapeseed cake application, particularly in sorghum. Principal component analysis using Biolog EcoPlate^TM data indicated that biochar application changed the microbial community structure in soil, particularly sorghum-grown soil. The changes in microbial community structure in sorghum were considered to be at least partly affected by changes in soil pH due to interaction between plant and biochar under organic manure application. Biochar application had little effect on the profile of ammonium-acetate-extractable mineral elements in soil including calcium, potassium, magnesium, sodium and sulfur with both types of manure application under soybean. Under sorghum, however, biochar with rapeseed cake manure application altered the profile. This alteration is attributable to an increase in the extractable concentration of certain metals in the soil including aluminum, cadmium and zinc, possibly caused by enhanced organic matter decomposition producing metal-chelating organic compounds. These different changes in the soil properties by biochar application may be directly or indirectly related to the different growth responses of different plant species to biochar application under organic manure application.     

Tolerance of barley cultivars to an acid,aluminum‐toxic subsoil related to mineral element concentrations in their shoots

Abstract

Barley, Hordeum vulgare L., is extremely sensitive to excess soluble or exchangeable aluminum (Al) in acid soils having pH values below about 5.5. Aluminum tolerant cultivars are needed for use in rotations with potatoes which require a soil pH below 5.5 for control of scab disease. They are also potentially useful in the currently popular “low input, sustainable agriculture (LISA)”; in which liming even the plow layer of soil is not always possible or cost effective, or in situations where surface soils are limed but subsoils are acidic and Al toxic to roots. Ten barley cultivars were screened for Al tolerance by growing them for 25 days in greenhouse pots of acid, Al‐toxic Tatum subsoil (clayey, mixed, thermic, typic Hapludult) treated with either 750 or 4000 μg?g^‐1 CaCO₃ to produce final soil pH values of 4.4 and 5.7, respectively. Based on relative shoot dry weight (weight at pH 4.4/weight at pH 5.7 X 100), Tennessee Winter 52, Volla (England), Dayton and Herta (Denmark) were significantly more tolerant to the acid soil than Herta (Hungary), Kearney, Nebar, Dicktoo, Kenbar and Dundy cultivars. Relative shoot dry weights averaged 28.6% for tolerant and 14.1% for sensitive cultivar groups. Comparable relative root dry weights were 41.7% and 13.7% for tolerant and sensitive cultivars, respectively. At pH 4.4, Al concentrations were nearly three times as high in shoots of sensitive cultivars as in those of the tolerant group (646 vs. 175 μg?g^‐1), but these differences were reduced or absent at pH 5.7. At pH 4.4, acid soil sensitive cultivars also accumulated phosphorus concentrations that were twice as high as those in tolerant cultivars (1.2% vs. 0.64%). At pH 5.7, these P differences were equalized at about 0.7% for both tolerant and sensitive groups. At pH 4.4, shoots of the Al‐sensitive cultivar Nebar contained 1067 μg?g^‐1 Al and 1.5% P. Concentrations of Al and P in the shoots of acid soil sensitive cultivars grown at pH 4.4 exceeded levels reported to produce toxicity in barley. The observed accumulation of such concentrations of Al and P in the shoots of plants grown under Al stress is unusual and deserves further study.     

Effect of calcium carbonate as determined by lime requirement buffer pH methods on soil characteristics and yield of sorghum plants

Abstract

A primary limit to crop production in extended regions of northern Greece is the infertility of acid soils, especially nutrient element unavailability or toxicity. An experiment was conducted to determine under greenhouse conditions which buffer pH method selected in a previous laboratory experiment is best suited to predict the lime requirement (LR) of acid soils which is most appropriate in relation to plant growth and nutrient element uptake of sorghum plants. The lime needs of three naturally occurring acid soils were estimated by three methods: Adams‐Evans (AE), Shoemaker‐McLean‐Pratt single buffer (SMP‐SB), New Woodruff (NWOOD), and the calcium hydroxide [Ca(OH)₂] equilibration procedure. Two greenhouse experiments were conducted: (i) Experiment I during the 1996 season with ORESTIAS a sandy loam soil, and (ii) Experiment II during 1997 and 1998 season with XANTHI a loam sandy soil and DRAMA a sandy clay loam soil, respectively. The following results were obtained. Differences were noticed between the soils as well as within the LR methods. The ORESTIAS soil needed 63% more calcium carbonate (CaCO₃) than the XANTHI soil and 70% more than DRAMA soil to achieve the target pH. Among the three LR methods, results showed that in two of the three soils the highest LRs were determined by the NWOOD and the lowest by the Ca(OH)₂ methods. After six weeks of incubation, no one method gave exactly the needed amounts of CaCO to achieve the target pH, the estimated amounts being mostly higher than tiiat needed except for the DRAMA soil. Among the methods, in general the SMP‐SB method predicted lime rates that raised the soil pH nearest to the target pH and the NWOOD soil seemed to be the more consistent for the three soils. The smallest LRs were predicted by the Ca(OH) method. Based upon plant production and nitrogen (N) uptake in the 1996 season, the shoot yields were significantly higher using the SMP‐SB method and lower with the NWOOD method. Similar results were obtained for the XANTHI and DRAMA soils during the 1997 season. On the contrary in the 1998 season (2nd experimental year), the highest yields were obtained with the NWOOD buffer method. For the 1996 and 1997 seasons, tissue N concentrations were partly significantly higher using the SMP‐SB method. In the 1998 vegetation period, the N concentrations were low and the control plants had significantly higher N contents.     

Sulfuric acid effects on iron and phosphorus availability in two calcareous soils

An attempt was made to study the effects of sulfuric acid additions to iron (Fe)‐ and phosphorus (P)‐deficient calcareous soils. Several greenhouse experiments were conducted with sorghum (Sorghum bicolor L.) grown in two calcareous soils. Addition of sulfuric acid to soils increased soil acidity, salinity, DTPA‐extractable Fe, available P (NaHCO₃‐extractable), and crop yield. The change in soil pH is the primary cause of increased nutrient availability and thus crop yield. Leaching after acid application is highly beneficial in decreasing salinity during germination and seedling stages and therefore has a direct impact on the yield. The beneficial effects of acid carried over for at least two greenhouse cropping seasons (approximately 4.5 months).     

The influence of soil pH on sorghum grain yields

Abstract

Sorghum bicolor (L.) Moench is sensitive to acid soil stress environments. Acid soil stress tolerance is quite complex and involves additively inherited characteristics dealing with aluminum and manganese toxicities and calcium, magnesium, and phosphorus deficiencies. Genotype‐by‐environment interactions in unstressed environments are normally high for yield parameters and stress environments escalate the problem. Thirty parental lines and hybrids were compared in the field at mean H₂O/KCI pH values of 6.6/5.9, 5.7/5.0, 5.0/4.6, and 4.4/4.1 from 1982–1988 on a Suches clay loam (Fluventic Dystrochrept). All yield data were compared against IS7173C (SC283), an internationally tolerant check. Mean yields decreased 19% as pH dropped from 6.6/5.9 to 5.0/4.6. Yields were reduced 67% as pH dropped from 5.0/4.6 to 4.4/4.1 which reinforced previous research indicating that soil pH must be below pH 4.9 (H₂O) and have less than 5% organic matter for proper acid soil stress screening and evaluation of sorghum. Soil aluminum saturation values averaging 50% provide a maximum level of stress for sorghum. Hybrids and parental lines responded differently to stress, with the most stable producer across environments and highest‐yielding hybrid being ASC599×GP140. Percent relative yield of SC283 and tolerance indices (low yield + high yield) gave parallel results and were particularly indicative of previous genotypic field responses. Hybrid combinations involving specific parental lines governed relative tolerance of each genotype.     

A decade of non-sorted solid urban wastes inputs safely increases sorghum yield in periurban areas of Burkina Faso

Abstract

Non-sorted solid urban wastes (SUW) are used by periurban cereal farmers in Africa. There is however limited information on how these SUW affect soil quality and cereal production and quality. In order to answer this question we identified around Ouagadougou (Burkina Faso) sites cultivated with sorghum (Sorghum bicolor (L.) Moench) that had received SUW for less than 5 years, for more than 5 years and less than 10 years and for more than 10 years. We sampled soils at 0–15 and 15–30 cm depth and we analysed pH, total carbon (C), nitrogen (N) and inorganic phosphate (P) content and P and heavy metals availability. We also measured at some of these sites sorghum production and nutrient and metal contents in sorghum grain and straw. Our results show that the 0–15 cm horizon of the soils that had received SUW for less than 5 years had lower pH, available P and heavy metals contents and produced lower yields than those that had been amended with SUW for more than 10 years. Maximum grain yield was observed in the sites that had been amended for more than 5 years but less than 10 years. There were no clear effects of SUW application time on the heavy metal contents of sorghum grain and straw. The increases in nutrient and heavy metals content observed in the 15–30 cm horizon of soils that had been amended for more than 10 years point out to the risks of element transfer to deeper horizons. Our results suggest that a complete sorting of organic matter from SUW and its further composting as presently recommended, is not necessary. Simply removing dangerous items from the SUW such as plastics, glass and batteries, would be sufficient. Adding this sorted substrate for 5 to 10 years to cereal fields would be sufficient to reach optimal yields, thereafter this substrate should be added to other surfaces.     

Agronomic effectiveness of phosphate rock and superphosphate for aluminum‐tolerant and non‐tolerant sorghum cultivars

Abstract

About 35% of soils in Venezuela are acid and low in available phosphorus (P). To solve this problem farmers lime and apply phosphate fertilizers to the soils, but both lime and fertilizers are expensive. A good alternative to overcome soil acidity is the use of aluminum (Al)‐tolerant cultivars. The objective of this study was to test the hypothesis, by use of a pot experiment, that sorghum cultivars tolerant to Al toxicity are able to use P from phosphate rock more efficiently than are susceptible cultivars. Three sorghum (Sorghum bicolor L. Moench) cultivars, Chaguaramas III (Ch), AI‐tolerant, Decalb D59 (D59), and Pioneer 8225 (Pi), both Al‐susceptible, were grown in the greenhouse for 20 and 35 days in two acid soils fertilized with 0 and 100 mg P kg^‐1 as triple superphosphate (SP) and Riecito phosphate rock (PR). Santa Maria soil was very low in available P (2 mg kg^‐1) and highly saturated in Al saturation (64.5%) and Pao soil was higher in available P (20 mg kg^‐1) and low in Al saturation (6.5%). Chaguaramas dry matter production, P uptake and root length was higher in Santa Maria soil as compared with Pi and D59 when grown with both SP and PR fertilization. Chaguaramas response to PR in Pao soil was not as good as in Santa Maria soil. The results of our experiment suggest that Al‐tolerant Ch is able to utilize P from PR more efficiently in soils like Santa Maria than Al‐susceptible cultivare Pi and D59.     

Evidence for the existence of different uptake mechanisms in soybean and sorghum for iron and manganese

A greenhouse experiment was conducted in which four varieties of soybean (Glycine max L.) and three varieties of sorghum (Sorghum bicolor L. Moench) were grown in a calcareous soil with and without soil applied FeEDDHA (0 and 2 mg Fe/kg soil). Soil applications of FeEDDHA increased Fe concentrations and reduced Mn concentrations in all varieties of soybean and eliminated Mn toxicity symptoms in Corsoy soybeans. Soil applications of FeEDDHA did not increase Fe uptake or affect Mn uptake into sorghum leaves. This study tends to support the hypothesis that there are distinct plant mechanisms between dicots and graminaceous species for the uptake of Fe, and that these mechanisms have a direct effect on Mn availability for plant uptake.     

Uptake of lead by coen from roadside soil samples

Abstract

The uptake of Pb by young, greenhouse grown corn plants from roadside soil samples was found to be not only dependent upon the total amount of Pb in the soil, but also upon the amount of Pb in the soil relative to the soils capacity to sorb Pb. This is in agreement with the uptake of Pb by corn grown on soils amended with PbCl₂, although plant accumulation of Pb from roadside soils was much less than from PbCl₂ amended soils at comparable Pb concentrations. The use of crushed limestone as a road building material which results in high soil pH values next to the roadside is probably responsible for the reduced plant availability of Pb in the roadside soils.     

Variability in growth and nutrient accumulation in sorghum grown in waterlogged soils

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is a potential crop for use in lowland paddy soils following rice in the Philippines. Little is known about the variability in sorghum germplasm with respect to yield potential in these soils, or the alterations in mineral uptake which might occur if late season rains resulted in waterlogging. Eight sorghum cultivars including the most widely used Philippine cultivar were grown after rice under flooded or non‐flooded conditions. Flooding was initiated 30 days after seeding and terminated when most cultivars were at or near the boot growth stage. Flooding markedly reduced dry matter production, and delayed bloom date on the average of 5.5 days. Grain yield was reduced about 57% over all cultivars. Early maturing cultivars were not reduced in days to bloom as much as the late maturing types, and there was a significant cultivar x treatment interaction for both bloom date and grain yield. Later maturing cultivars outyielded the other cultivars at physiological maturity in both flooded and non‐flooded conditions. Concentrations of the major nutrients N, P, K, Ca, Mg, and S were decreased in foliage at the boot stage due to flooding. The only nutrient to fall below published “critical” levels in leaf tissue, however, was N, and plants growing in these conditions showed classical N deficiency symptoms. Iron and Mn concentrations were significantly higher in foliage at the boot stage with flooding, but not high enough to be considered toxic. Most differences observed at boot still existed at maturity, but of less magnitude. Marked variability existed in the response among cultivars to waterlogging. It would appear that flooding tolerant genotypes could be selected which would improve existing cultivar choices for use in these difficult soils.     

Soybean response to the application of several elements on a low‐manganese soil

Abstract

Certain soils in the Lower Atlantic Coastal Plain are Mn‐deficient and because of their inherent properties, deficiencies of other elements might be expected. The response of soybean [Glycine max (L.) Merr. cv. ‘Ransom'] to annual soil applications of B, Cu, Fe, Mo, S, and Zn with and without Mn was examined. The study was conducted on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) in 1975, 1976, and 1977. Seed yields, and soil and plant tissue concentrations of certain of the applied elements were determined. Soil pH increased from 6.4 in 1975 to 7.0 in 1977 as a result of lime applications.

Of the seven elements studied, only Mn significantly increased soybean seed yield compared to the check. Leaf concentrations of the respective elements were higher where the element was added than they were in plants grown on the check plots. In 1977, after three years of elemental additions, plant concentrations of Mn, Cu, and Zn were higher, relative to checks, than in 1975. In 1977, with the higher soil pH levels, plants from check plots had lower concentrations of Mn, but unexpectedly equal levels of Cu and higher levels of Zn than in 1975. This unexplained increase in plant Zn was also found in Other experiments in the same field during the same time period. Double acid extracted more soil Mn, Cu, and Zn than did DTPA from similar treatments during all three years. The DTPA‐extractable soil Mn correlated much better with plant Mn than did double acid Mn values, especially over years where a change in soil pH occurred. Correlation coefficients comparing extractable soil versus plant values for Cu and Zn data combined over years were higher for double acid than DTPA, although coefficients for the Cu and Zn data were still generally much lower than for the Mn data.     

Growth and nutrient uptake in grain sorghum grown under mulch

Mulches can alter plant growth by changing the soil environment, but their effects on mineral uptake in grain sorghum are unknown. A 3‐year study was conducted to measure nutrient uptake in plants grown under 0, 2200, 4400, and 8800 kg/ha mulch. Plants were irrigated to insure that moisture was not limiting. Dry‐matter production, total mineral uptake and concentrations were determined at 7‐ to 9‐leaf, late boot, soft dough, and physiological maturity growth stages. Mulches altered sorghum growth by delaying plant maturity and by increasing dry‐matter yields. Nutrient uptake increased with increased dry‐matter production although elemental concentrations declined. Hybrid reaction to mineral uptake was dependent on the specific environment created by the mulch. Hybrids did not respond the same to given mulch rates each year. Management considerations for soil fertility under mulch conditions should be made on the basis of expected dry‐matter yields for the specific environment.     

Greenhouse evaluation of growth parameters related to birdsfoot trefoil and red and white clover production on an and IC mission silt loam

Abstract

Birdsfoot trefoil (Lotus tenius), red clover (Trifolium pratense) and white clover (Trifolium repens) were evaluated as potential forage legumes on andic soils. A greenhouse study was used to evaluate the influence of soil pH on: (1) the establishment and growth of these forage legumes, (2) N and P quantity and concentration, and (3) Rhizobium lupini and Rhizobium trifolii survival.

Aluminum sulfate and finely‐ground calcium carbonate were used to adjust soil pH. Soil pH's were 4.8, 5.1, 5.6, 6.2, 6.4, 6.9, 7.0 and 7.4. Birdsfoot trefoil, red clover and white clover were grown in 15 cm pots in the greenhouse and harvested five times at approximately 20‐day intervals. Yield was measured and plant material was analyzed for total N and P. Populations of R. lupini and R. trifolii were monitored using the MPN technique.

Manipulation of pH in the Mission soil was found to have a significant effect on the growth of the three forage legumes, tissue N and P concentration and uptake, and on the survival of R. lupini and R. trifolii in the soil. In general, tested parameters increased with increasing soil pH. Greatest forage yield occurred in the 6.9–7.0 pH range. The andic nature of the Mission soil requires a pH adjustment above pH 6.2 for acceptable establishment and yields of the three forage legumes studied. This is in sharp contrast to non‐andic northern Idaho soils where forage legume yields are usually not adversely affectea above pH 5.5. All three legumes appeared to have good potential ana should be evaluated under field conditions.