Effect of molybdenum,phosphorus, and lime application to acid soils on dry matter yield and molybdenum nutrition of lentil

Deficiency of molybdenum (Mo) in acid soils causes poor growth of pulses. An experiment was, therefore, conducted in greenhouse to study the effect of Mo, phosphorus (P), and lime application on the dry matter yield and plant Mo concentration of lentil (Lens esculenta L.) in two Mo‐deficient acid alluvial soils. The experiment was conducted using a factorial design with three levels of lime (no lime, half, and full lime requirement), three levels of P (0, 25, and 50 mg kg^‐1), and two levels of Mo (0 and 1.0 mg kg^‐1). Plants were grown for 60 days and at harvest their dry matter yield and Mo concentration were recorded. The three treatments significantly increased dry matter yield, Mo concentration and Mo uptake, the increase being most pronounced with Mo application followed by lime and P. Increases due to applied Mo were greater in presence than in absence of added P; while the reverse was true with the liming treatments. Liming and P application at their lower levels also interacted positively for better Mo nutrition of plants. Results thus indicated that the severity of Mo deficiency in the lentil plants may be reduced by lime and P application in Mo‐deficient acid alluvial soils.     

Dry matter and primary nutrient accumulation in soybeans as affected by combined Nitrogen levels

Nodulating and non‐nodulating soybeans were grown on a Alfic Udipsamment and a Typic Hapludoll amended with 10 or 100 kg N/ha. Tissue and grain samples were analyzed to determine N₂‐fixation, dry matter, and N, P, and K accumulation. Highest grain yields were associated with the highest levels of N₂‐fixation and N and K accumulation in grain. The largest dry matter production was by nodulating plants grown on a high soil N regime. Nodulating plants accumulated more grain and tissue N, P, and K than non‐nodulating plants. Nitrogen stress increased P concentrations in both grain and tissue and decreased harvest indices.     

Plant growth response to applied k on coarse‐textured feldspathic soils

Abstract

An experiment was conducted to determine the influence of continuous cropping and K fertilization on plants grown on coarse‐textured soils high in feldspars. The A and C horizons of Elsmere (sandy, mixed, mesic Aquic Haplustoll), Valentine (mixed, mesic Typic Ustipsamment) and Sharpsburg (fine, montmorillonitic, mesic Typic Arguidoll) soils were continuously cropped in the greenhouse with annual ryegrass (Lolium multiflorum Lam.). Four K treatments (0, 18.5, 37.5 and 75.0 mg K/kg soil) were applied before planting. At approximately 4 week intervals, above ground plant tissue was harvested and analyzed for K content for a total of 12 cuttings. Potassium deficiency symptoms (marginal necrosis, spotting) eventually appeared in plants grown on all but the A horizon of the Sharpsburg soil. Continuous cropping decreased plant K concentration, averaged across all treatments, from 38 to 10 g/kg dry matter. Potassium fertilization increased K concentration in plant dry matter on the soils initially low in slowly available and exchangeable K, but did not increase biomass. Uptake was higher by plants grown on A horizons. Different K rates resulted in different cumulative K uptake on the soils initially low in available K.     

Hybrid ryegrass response to acid soil treatment with calcitic and dolomitic lime

Abstract

Since ryegrass (Lolium sp.) is a widely grown cool‐season forage grass, its magnesium concentration is of special interest to ruminant livestock producers. This study was conducted to investigate the effect of calcitic or dolomitic lime addition on dry matter yield and mineral composition of hybrid ryegrass, Lolium (multiflorum x perenne x perenne) grown in eight acidic soils. Each soil received two levels of calcitic or dolomitic lime, L(C₁) and L(C₂) or L(D₁) and L(D₂), which raised pH to approximately 5.3, and 6.0. Dry matter yield response was obtained only in soils having an initial % Al saturation ≥59, % Mg saturation ≤10 and % Ca saturation ≤21. Only in one soil, which had an initial exchangeable Mg level of 0.05 cmol_c/kg of soil, was response to dolomitic lime higher than that obtained with calcitic lime. Magnesium concentration in dry matter was increased by both levels of dolomitic lime with the increase dependent on the rate used and on the initial level of exchangeable Mg. The average Mg concentration increased from 0.8 to 3.9 g/kg, from 1.6 to 3.6 g/kg, and from 2.6 to 3.9 g/kg, when ryegrass was grown in soils having low, medium, and high initial exchangeable Mg levels, respectively. Mg concentration in the ryegrass tended to be lower in the unlimed soils than when calcitic lime was used, 1.1 vs. 1.4 g/kg, when the soils had low to medium exchangeable Mg levels. The results suggest that if ryegrass is to be grown in acidic soils containing low to medium levels of exchangeable Mg, the use of dolomitic lime is desirable, even if no yield response to applied Mg is expected, to decrease the probability of the Mg deficiency disease, hypomagnesemia, in ruminant animals.     

Effect of Lime and Flooding on Phosphorus Availability and Rice Growth on Two Acidic Lowland Soils

Abstract

Loss of soil‐water saturation may impair growth of rainfed lowland rice by restricting nutrient uptake, including the uptake of added phosphorus (P). For acidic soils, reappearance of soluble aluminum (Al) following loss of soil‐water saturation may also restrict P uptake. The aim of this study was to determine whether liming, flooding, and P additions could ameliorate the effects of loss of soil‐water saturation on P uptake and growth of rice. In the first pot experiment, two acid lowland soils from Cambodia [Kandic Plinthaqult (black clay soil) and Plinthustalf (sandy soil)] were treated with P (45 mg P kg^?1 soil) either before or after flooding for 4 weeks to investigate the effect of flooding on effectiveness of P fertilizer for rice growth. After 4 weeks, soils were air dried and crushed and then wet to field capacity and upland rice was grown in them for an additional 6 weeks. Addition of P fertilizer before rather than after flooding depressed the growth of the subsequently planted upland rice. During flooding, there was an increase in both acetate‐extractable Fe and the phosphate sorption capacity of soils, and a close relationship between them (r²=0.96–0.98). When P was added before flooding, Olsen and Bray 1‐extractable P, shoot dry matter, and shoot P concentrations were depressed, indicating that flooding decreased availability of fertilizer P. A second pot experiment was conducted with three levels of lime as CaCO₃ [to establish pH (CaCl₂) in the oxidized soils at 4, 5, and 6] and four levels of P (0, 13, 26, and 52 mg P kg^?1 soil) added to the same two acid lowland rice soils under flooded and nonflooded conditions. Under continuously flooded conditions, pH increased to over 5.6 regardless of lime treatment, and there was no response of rice dry matter to liming after 6 weeks' growth, but the addition of P increased rice dry matter substantially in both soils. In nonflooded soils, when P was not applied, shoot dry matter was depressed by up to one‐half of that in plants grown under continuously flooded conditions. Under the nonflooded conditions, rice dry matter and leaf P increased with the addition of P, but less so than in flooded soils. Leaf P concentrations and shoot dry matter responded strongly to the addition of lime. The increase in shoot dry matter of rice with lime and P application in nonflooded soil was associated with a significant decline in soluble Al in the soil and an increase in plant P uptake. The current experiments show that the loss of soil‐water saturation may be associated with the inhibition of P absorption by excess soluble Al. By contrast, flooding decreased exchangeable Al to levels below the threshold for toxicity in rice. In addition, the decreased P availability with loss of soil‐water saturation may have been associated with a greater phosphate sorption capacity of the soils during flooding and after reoxidation due to occlusion of P within ferric oxyhydroxides formed.     

Calcium requirements for peanuts

Abstract

Surface soils from ten soil series representing five great groups were collected from Alaska. These soils were selected from the important agricultural areas covering a wide geographic distribution. These soils can be divided into two distinct groups based on their parent material: loess and volcanic ash. Phosphorus sorption maxima were calculated based on the Langmuir isotherms. The volcanic ash soils (Cryandept and Cryorthods) showed an average P‐sorption maxima of 10,122 mg/kg and loess soils averaged 3,934 mg/kg. Both groups have similar portions of phosphorus in the organic form (19%) and occluded form (8 to 9%). The nonoccluded‐P in the volcanic ash soils and the loess soils was 68% and 43% respectively, and the Calcium‐P was 4% and 29% respectively.

Regression analysis indicated that aluminum and iron are primarily responsible for P‐sorption. The dithionite extractable Al is responsible for P‐sorption in volcanic ash soils, while oxalate extractable Al is responsible for P‐sorption in loess soils. Dithionite and oxalate extractable Fe probably play a secondary role in P‐sorption. The sorption isotherm, regression analysis and the P‐fractionation data provide the agronomist with useful information to estimate P requirement of newly cleared soils.     

Boron utilization by potato in nutrient cultures and in field plantings

Abstract

Analysis of soil and plant tissue for boron (B) is routine, but more information is needed to clarify the interpretations of test results as a basis for B fertilization of potato (Solarium tuberosum L.). Experiments were conducted in nutrient cultures and in the field to relate the utilization of B by potato plants to visual symptoms of deficiency and toxicity. Without added B the nutrient cultures produced B‐deficient potato plants, but the field plots with 0.3 to 0.4 mg of hot water soluble B/kg of soil did not. Plant shoots from nutrient cultures had a minimum of 13 mg B/kg as compared with plants in field plots with 30 mg B/kg in vines. Concentrations to 50 mg B/kg of dry matter were obtained in plant shoots from nutrient cultures with 1 mg B/L added and in field‐grown plants fertilized with 2.2 kg B/ha. Toxicity to B appeared or was eminent from either adding 3 mg B/L or more to nutrient solutions or 4.5 kg B/ha or more to the field plots. These results suggest the feasibility of developing critical nutrient (sufficiency) ranges for B in plant shoots and vines.     

Sulfur status of volcanic ash‐derived soils in Hawaii

Abstract

Several rainwater samples and 14 profiles of Hawaii's volcanic ash‐derived soils were analyzed for sulfur (S). Atmospheric deposition was an important S source at the coast (24 kg S/ha), but its contribution decreased with increasing distance from the sea (1 kg S/ha at 24‐km inland). The S concentration of rainwaters also decreased linearly with increasing rainfall.

Several thousand mg SO₄‐S/kg can be extracted from many volcanic ash‐derived soils of Hawaii, and it was often required at least four extractions [0.04 M Ca(H₂PO₄)₂, 1:10 soil to solution ratio] to completely desorb this SO₄. There was a close association of high SO₄ retention with high rainfall. This might have resulted from (1) the development of a solid phase with high SO₄ retention under intense weathering conditions, (2) more total SO₄ received by the soils from atmospheric deposition, and (3) past fertilization of sugarcane grown in high rainfall areas.

Low concentrations of soil solution SO₄‐S in relation to large amounts of P‐extractable SO₄ suggest that a S bearing mineral, such as basaluminite, may be controlling soil‐solution SO₄. Furthermore, SO₄ adsorption isotherms of these volcanic soils generally show a bi‐phasic property, and suggest that 40 to 80 mg SO₄‐S/kg is required to maintain 3 ‐ 6 mg SO₄‐S/L in the soil solution, a concentration range considered adequate for the growth of most crops.     

Effect of magnesium fertilization on yield and leaf composition of tomato plants

Tomato plants were grown for 2 years at 4 different rates of Mg fertilization on a Princeton loamy sand at pH 4.8 with 29 kg exchangeable Mg/ha. Calcareous limestone was used to provide a pH treatment in the second year. Magnesium deficiency symptoms were observed on plants grown on plots having ≤ 38 kg/ha NH₄OAC‐extractable Mg. Application of 56 kg Mg/ha corrected Mg deficiency and produced a significant increase in yield. Application of calcitic limestone also produced significant yield increases, but did not affect the development of Mg deficiency symptoms. Tomato yield was increased 27.9% by Mg application and 17.7% by lime application. Highest tomato yield was obtained with application of 112 kg Mg/ha. Symptoms of Mg deficiency were observed when the Mg concentration in recently mature leaf tissue was in the 0.30 to 0.32% range. Magnesium concentration in leaf tissue increased linearly with increasing Mg rate. Leaf Mg concentration at various growth stages of the tomato plant was variable depending on Mg treatment. Magnesium fertilization rate bad little effect on Ca or K leaf concentrations. Application of Calcltic limestone increased leaf tissue Ca and reduced leaf tissue Mg and Mn concentrations.     

The influence of mount St. Helens volcanic ash on alfalfa growth and nutrient uptake

Abstract

Concern has been expressed that large amounts of volcanic ash from the May 18, 1980 eruption of Mount St. Helens may have created potential nutritional problems associated with forage production in northern Idaho and eastern Washington to the extent that adjustments need to be made in soil test correlation data. The objectives of this greenhouse study were to: (1) determine the effect of varying amounts of volcanic ash mixed into soils of northern Idaho on total alfalfa biomass production, and (2) to determine the effect of various soil/ash mixtures on the nutrient concentrations of P, K, S, Ca, Mg, Mn and Zn in alfalfa.

Alfalfa was grown in eight different northern Idaho soils amended with differing levels of volcanic ash (0, 20, 35, 50 and 75%) in the greenhouse. The alfalfa seeds were inoculated and fertilizer P and S were added to all treatments. Total plant biomass and P, K, S, Ca, Mg, Mn and Zn plant concentrations were measured.

The eight soils were pooled for analysis and it was found that increasing amounts of volcanic ash increased alfalfa biomass production. Plant P, S, Ca, Mg and Zn concentrations also increased with increasing levels of ash. Conversely, increasing levels of ash resulted in lower alfalfa tissue K and Mn concentrations. There is no evidence to suggest that the highest levels of ash which fell in northern Idaho (700,000 kg/ha) inhibited alfalfa production. Consequently, there is no need for adjustments in soil test calibration data presently used for fertilizer recommendations for alfalfa.     

Ryegrass forage yield and quality response to sulfur and nitrogen fertilizer on coastal plain soil

Abstract

Sulfur (S) deficiency has been reported in some upland soils of the southern United States and S application has improved forage quality on the low‐S soils. A field experiment was conducted for three years to determine ryegrass (Lolium multiflorum L.) dry matter yield and forage quality response to S fertilization. Prilled elemental S was applied each year at two rates (0 and 45 kg S/ha) in combinations with three rates of nitrogen (N) (168, 224, and 280 kg/ha). Wet depositions of S in rain were monitored over the seasons. Sulfur fertilization generally did not increase seasonal dry matter yield and plant uptake of S. Nitrogen application generally increased dry matter yield and protein content during the season. Averaged over the three‐year period, however, forage yield and S uptake increased from 7.7 to 10.5 Mg/ha and 13.9 to 18.8 kg/ha, respectively, as N fertilization increased from the lowest to highest treatment rates. Forage dry matter for each harvest ranged from 0.6 to 2.2 Mg/ha, while S, protein, in vitro dry matter digestibility (TVDMD), and N/S ratio tended to decline seasonally from 2.5 to 1.8, 266 to 142, and 795 to 716 g/kg, and 17.8 to 11.9, respectively. Sulfur input from rainfall was small with a three‐year average of 5.8 kg/ha (±0.64 SE). In some locations of the southern United States, S may not be limiting even when applying high rates of N to high‐yielding forages which annually remove large quantities of S. Because of the lack of yield response from S application and low inputs of S from wet deposition, S from sources other than rainfall may have been considerable.     

Correlation of Soil pH and Mehlich‐3 Phosphorus with Postflood Rice Phosphorus Concentrations in Arkansas

Abstract

Plant‐available phosphorus (P) measured by routine soil‐test methods is poorly correlated with rice grain yield in Arkansas. Our objective was to determine whether soil water pH (pH_w) and Mehlich‐3 P were correlated with growth and yield of rice grown on silt loam soils. Data from 35 field studies were used to correlate Mehlich‐3 P and pH_w with relative yield, dry matter accumulation, and P concentration at the midtillering stage. Significant linear or nonlinear relationships between pH_w or Mehlich‐3 P with rice growth parameters were delineated but explained less than 27% of the variability in dry matter and P concentrations at the midtillering stage and grain yield at maturity. Mehlich‐3 P and pH_w together explained 61% of the variability in midtillering P concentrations. Midtillering whole‐plant P concentrations were positively related to relative grain yield and dry matter production and will be used to identify soils with limited P availability for rice in Arkansas.     

The effect of lime levels on the growth of beans and maize and nodulation of beans in three tropical acid soils

Abstract

A study to investigate the effect of lime on dry matter yield of maize (Zea mays) and beans (Phaseolus vulgaris) and nodulation of beans grown in three tropical acid soils (two humic Nitosols and one humic Andosol) was carried out in a greenhouse. The soils ranged from 4.2 to 5.0 in pH; 1.74 to 4.56 in %C; 21.0 to 32.0 meq/100g in CEC; 5.10 to 8.10 meq/100g in exchange acidity; 0.60 to 3.20 meq/100g in exchangeable (exch.) Al and 0.13 to 0.67 meq/ 100g in exch. Mn.

Exchange acidity and exch. Al decreased with increasing levels of lime in the three soils. Exchangeable Al was reduced to virtually zero at pH 5.5 even in the soils which had appreciable initial amounts. Exchangeable Mn also decreased with increasing levels of lime in the two Nitolsos. Exceptional results, however, were obtained with the Andosol where exch. Mn increased ten‐fold with the first level of lime and then decreased with subsequent levels.

In all the soils, mean dry matter yield of beans and maize, and mean nodule dry weight of beans generally increased significantly with increasing lime levels up to pH value of 6.0. The dry matter yield of beans and maize, and nodule weight of beans, however, decreased progressively with increasing lime levels beyond pH 6.0 value. pH range of 5.5 to 6.0 was considered optimum for the growth of maize and beans, and nodulation of beans in these soils.     

Effects of liming on yield,forage cation composition,and tetany potential of wheat in Kansas

Abstract

We studied the effects of liming on dry matter production, nutrient composition, and grain yields of wheat in field experiments conducted on two soil types at three locations during the 1976–77 and 1977–78 growing seasons. Lime sources were commercial agricultural lime, finely divided stack dust, and dolomitic limestone (which contained 10.6% Mg). Lime applied at 2,800 kg/ha in the 1976–77 and 10,750 kg/ha in the 1977–78 experiments provided Mg from the dolomite at rates of 300 and 1,140 kg/ha, respectively.

Soil pH was significantly increased by liming, but Mg saturation percentages were significantly greater only at the 1,140 kg/ha rate. Forage dry matter and grain yields were not increased by lime applied at the lower rate, but significant increases were found in dry‐matter production in the late fall and spring samplings of the 1977–78 experiment. Those increases in plant growth and dry matter production were probably due to reductions in the soluble Mn and Al concentrations in the soil. Forage N and P concentrations were generally not influenced by liming. Potassium concentrations in forage from the limed plots were usually equal to or greater than those in forage from unlimed plots. Calcitic limestone sources generally increased forage Ca concentrations, but liming with dolomite more often than not depressed Ca concentrations below levels found in the check plots. Dolomite, when applied at the 1,140 kg/ha rate, effectively increased the forage Mg concentration, although the concentration exceeded 0.2% only during the early growth stages. Liming generally showed no significant reduction in the tetany potential of the wheat forage as predicted by the equivalent ratio K/(Ca + Mg).     

Wheat grown on volcanic ash with slow releasing nitrogen fertilizer and amended with sewage sludge compost

Abstract

The volcanic ash of the Mount Pinatubo in Philippines is used in this study. The major drawbacks of this volcanic ash for growing agricultural crops are nitrogen (N) and iron (Fe) deficiencies with low organic matter contents. The objective of this study is to investigate the effect of sewage sludge compost on wheat through shoot and root development as well as dry matter production by pot culture. Either oxamide or polyolefinresin‐coated urea (PORCU) along with potash and phosphate fertilizers is applied to each pot containing volcanic ash. Application of sewage sludge compost in oxamide treatment yield a better plant height with an extended root length and high dry matter production compared to PORCU. However, statistical analysis of the data on plant height shows significant level (p<0.001, n=36), while those on root growth and dry matter production show no significant difference (p<0.335 and 0.564, n=36). Thus it is concluded that the coupling effect of oxamide and sewage sludge compost has a greater impact on plants, while growing on this ash.     

Response of rice to basic slag,lime, and leaching in two saline-acid sulfate soils in pot experiments

Pot experiments were conducted to evaluate the effects of basic slag (6 to 18 t/ha), lime (CaCO₃: 3 to 9 t/ha), lime (3 t/ha) plus MnO₂ (100 mg/kg), and leaching (1.8 L/kg soils) on the growth, yield, and nutrition of rice plants grown on two saline-acid sulfate soils. The Sulfic Fluvaquent (Chakaria series) and Typic Sulfaquent (Badarkhali series) respectively showed low pH (4, 4.3); high electrical conductivity (16.2, 14.2 mS/cm), sodium adsorption ratio (13.6, 12.8), and water soluble SO₄2^? (4.6, 4.9 cmol/kg). The growth and yield response of rice to the treatments were found better in Chakaria than in Badarkhali soil. The leaching treatment was found to be the best to produce the maximum straw, and grain yield (869% increase over the control) and the highest dose of basic slag (18 t/ha) was ranked second (728%) in Badarkhali soil. But in Chakaria soil, the best response (928%) was determined with the highest dose of lime (6 t/ha) followed by the leaching (900%) treatment. The additional application of Mn0₂ (100 mg/kg) with lime (3 t/ha) significantly increased the straw and grain yields of rice by 42–47% compared with the lime 3 t/ha in both the soils. Similar effects were observed for N, P, and K concentrations in plant straw at maturity. Leaching, basic slag, and lime treatments exerted significant decrease of the Fe, Mn, Zn, and S concentrations in plants, increase of soil solution pH and optimization of some element concentrations in the plants and soil solutions.     

Residual effects of sewage‐sludge application on plant and soil‐profile chemical composition

Abstract

Long‐term effects on plant and soil‐profile chemical composition imposed by a residential sewage sludge were studied on an Oxisol from Hawaii. Sludge was applied at 0, 45, 90, and 180 Mg/ha in 1983. An NPK‐fertilized treatment was included for comparison. Sudangrass (Sorghum bicolorL. Moench) was grown as a test crop in the 1983–84 and 1986–87 seasons. Soil samples for chemical analysis were taken in 1987 at three depths: 0–23 cm, 23–46 cm, and 46–69 cm.

Beneficial effects of sludge, measured 3 years after application (beginning of the 1986's planting), were evident by large yield increases on sludge‐amended soils relative to the unamended and the NPK‐fertilized soils. The first cutting produced approximately 5 Mg/ha of dry matter from the sludge treatments, regardless of rate, as compared with 3 and 1.5 Mg/ha from the NPK and the 0 treatments. Regrowths showed similar effect, though less dramatic; average yields were 2.6 Mg/ha with sludge and 1.6 Mg/ha without.

Heavy‐metal concentrations in plants were generally unaffected by sludge applications; probably because (i) heavy‐metal contents of the sludge were low, and (ii) soil pH was increased by sludge.

Remarkable increases in pH, exchangeable Ca and extractable P, and resultant decreases in exchangeable Al, in all three soil layers of sludge‐amended soils suggest that surface application of a low heavy‐metal sludge could serve to correct subsoil acidity and enhance subsoil P availability.     

Heavy‐metal toxicity in plants 1. A crisis in embryo

Abstract

Heavy metals are often added indiscriminantly to soils in pesticides, fertilizers, manures, sewage sludges, and mine wastes, causing an imbalance in nutrient elements in soils. Heavy‐metal toxicity causes plant stress in various degrees dependent on the tolerance of the plant to a specific heavy metal. The objectives of this study were (i) to show that plant species and soils respond differently to heavy metals and (ii) to show the necessity for proper quantity and balance of heavy metals in soils for plant growth.

Three Fe‐inefficient and three Fe‐efficient selections of soybean, corn, and tomato were grown on two alkaline soils with Cu and Zn ranging from 14 to 340 and Mn from 20 to 480 kg/ha. Heavy‐metal toxicity caused Fe deficiency to develop in these plants. The Fe‐inefficient T3238fer tomato and ys₁/ys₁ corn developed Fe deficiency on all treatments and both soils. T3238FER tomato (Fe‐efficient) did not develop heavy metal toxicity symptoms on any treatment or soil. The soybean varieties and WF9 corn were intermediate in their response.

The unpredictable response of both the soil and the plant to heavy metals make general recommendations difficult. In order to maintain highly productive soils, we need to know what we are adding to soils and the consequences. Without some control, the continued addition of heavy metals to soils is a crisis in embryo.     

Grapevine Rootstock Effects on Lime‐Induced Chlorosis,Nutrient Uptake,and Source–Sink Relationships

Abstract

The experiment considered Vitis vinifera L. cv. “Pinot blanc” clone VCR5 grafted on a lime‐susceptible (3309 C) and a lime‐tolerant (41 B) hybrid rootstock and grown in 45 L pots of a calcareous and a non‐calcareous soil. Each treatment included plants bearing clusters and plants without clusters; in the latter case the bunches were removed 15 days before blooming. During the third growth year, shoot length, leaf chlorophyll (Chl), and mineral element concentrations were recorded. At the end of the growing cycle the grapevines were divided into leaves, shoots, berries, cluster stems, trunk, roots, and dry matter and mineral element composition per organ were analyzed. The 41 B rootstock showed its lime‐tolerance by exhibiting little reduction of shoot length when grown in the calcareous soil as compared to the non‐calcareous one, while 3309 C growing in the calcareous soil induced a dramatic shoot length reduction. The rootstock also affected the leaf chl concentration according to the known degree of lime‐tolerance/susceptibility: “Pinot blanc” grafted on 3309 C and growing on the calcareous soil showed chlorotic leaves while the plants grafted on 41 B had green leaves; cluster removal did not affect leaf chl. The fruit load (expressed as berry dry matter) was strongly affected by the soil and the rootstock; in the calcareous soil 41 B rootstock produced twice as high cluster dry matter than did 3309 C. A higher macronutrient uptake for the plants growing under lime‐stress conditions was affected by 41 B rootstock. Cluster removal in plants grown on calcareous soil produced different effects, as follows: in the case of 41 B rootstock, a redistribution of photosynthate to other sinks like shoot tip and roots occurred, while in the case of 3309 C only the roots benefited. Under lime‐stress condition the plants grafted on 41 B took up more iron (recorded as total amount in the leaves) than did those grafted on 3309 C.     

Influence of applied p on the cation exchange capacity of volcanic ash soils

Abstract

The CEC of volcanic ash derived soils in Guatemala was measured following equilibration with 1.5 and 6.0 me P/100 g soil supplied through KH₂PO₄ solutions. An increase in CEC resulted due to P reaction and the increase was substantial after removal of soluble Al from P reacted soils. The average ratios of increase in CEC to P retained were 0.49 and 1.63 in the former and later, respectively. P apparently neutralized positive charges on the surface of amorphous component and those internally in the soil particles resulting in a net increase in negative charge (CEC).