Ken-ichi Kakuda

Relationship between mineral composition or soil texture and available silicon in alluvial paddy soils on the Shounai Plain, Japan

Abstract To evaluate the relationship between the amount of available Silicon (Si) in paddy soils and their mineral properties on the Shounai Plain in Japan, which is formed from several parent materials, we evaluated the amount of available Si, the particle size distribution, the oxide composition of crystalline minerals and the amount of oxalate-extractable Si (Sio), iron (Feo) and aluminum (Alo) in the soil. The amount of available Si in the soil and the oxide content of the crystalline minerals differed among four soil groups that were distinguished by their clay mineral composition. There was no difference in the particle size distribution among the soil groups. The amount of available Si was positively related to the SiO2/Al2O3 ratio of clay, the CaO concentration of silt and fine sand, and the amounts of Sio, Feo and Alo in the soil. The amount of available Si in the soils was negative correlated with the Na2O and K2O concentrations of silt, the K2O concentration of fine sand, and the coarse sand content. These results suggest that the amount of available Si in soils is affected by the weathering resistivity of their minerals and that the particle size distribution and mineral composition are related to the available Si of the soils. Mineralogical properties, including the particle size distribution and mineral composition such as the SiO2/Al2O3 ratio × clay fraction content and the amounts of CaO and MgO in silt-sized particles, were positively correlated with the amount of available Si in the soil, but these correlations were not found for fine sand-sized particles. The Sio, Feo and SiO2/Al2O3 ratio × clay fraction contents contributed approximately 50% to the amount of available Si in the soils. The amount of available Si in the soil was divided into two groups according to the location of the paddy field. The amount of soil-available Si in the alluvial plain was affected by the geology upstream through the mineral composition.

Phosphorus application affects root length distribution and water uptake of upland rice in a column experiment

Abstract We investigated the effect of basal phosphorus application at 0–0.2 m depth (−P: 0 kg ha −1, +P: 120 kg P2O5 ha−1) on the root system development and water uptake pattern of upland rice (Oryza sativa L.). Applications were made toP-deficient soil, and plants were either irrigated or nonirrigated (subjected to short-term mild soil water stress) at the panicle initiation stage. P application enhanced the growth of nodal roots and medium-sized lateral roots (80–220 11-m in size). In the +P plants, root length per layer was longer in all the soil layers (p<0.01) and the percentage of the total root length located below 0.2 m depth was higher (−P: 18%, +P: 24% ). Under irrigated conditions, most of the water was extracted from 0–0.2 m depth regardless of the P level, and the water uptake rate from this layer and hence the total amount of water was higher in the +P than in the −P plants. Under water stress conditions, the water uptake at 0–0.2 m depth was lower than that under irrigated conditions, while the water uptake below 0.2 m depth was higher than that under irrigated conditions during the 0–2 d period after the imposition of stress in both −P and +P plants. Under water stress, since the water uptake from below 0.2 m depth was higher in the +P than in the −P plants, the total amount of water was higher in the +P plants. By promoting the development of deeper root systems and improving the water uptake below 0.2 m depth, basal P application at 0–0.2 m was found to be important for increasing the total water uptake by upland rice under mild soil water stress in phosphorus-deficient soils.

Growth and canopy structure of rice plants grown under field conditions as affected by Si application

Abstract In many studies using solution culture or pot culture it was reported that dry matter and yield production of rice plants can be improved by silicon application. There is limited information, however, on field-grown rice. The purpose of this study was to evaluate the effect of the application of Si (in the form of silica gel) on the growth, yield, and canopy structure of rice plants grown under field conditions. The results obtained were as follows: 1) No significant differences in the growth and yield of rice plants with and without Si application were observed under high availability of SiO2. However, the canopy structure of the rice plants was improved by Si application. The distance between the desirable position and the actual position of the top leaf was shorter in the + Si treatment than in the − Si treatment at the maximum tiller number stage. 2) The relative light intensity was higher in the + Si treatment than in the − Si treatment at the maximum tiller number stage, irrespective of the plant height. At the booting stage, the relative light intensity in the upper canopy was lower in the + Si treatment than in the − Si treatment. A higher rate of Si gave a lower light extinction coefficient at the maximum tiller number stage.

The fate of ammonium nitrogen applied to flooded rice as affected by zeolite addition

Abstract High rice (Oryza sativa L.) yields are closely related to plant absorption of a large amount of nitrogen (N). However, there is little information on the fate of N applied at the middle growth stages of rice. Labeled 15N ammonium sulfate was applied at the panicle formation stage in Experiment I, and 10 d after heading in Experiment II. Zeolite was also added at the concentration of 0, 0.01, and 0.1 kg kg-1 to increase the cation exchange capacity (CEC) of the soil. The amount of 15N fertilizer in the soil surface water decreased exponentially and the fertilizer disappeared within 2 d after application. The soil that received zeolite at 0.1 kg kg-1 exhibited significantly less 15NH4 +-N in the surface water and in the soil solution than the soil without the zeolite amendment. A significantly larger amount of exchangeable 15NH4 +-N was observed in the high zeolite-treatment of soil compared to the low zeolite-treatment of soil. The amount of exchangeable 15NH4 +-N increased initially, and thereaft...

Nutrient Availability and Response of Sago Palm (Metroxylon sagu Rottb.) to Controlled Release N Fertilizer on Coastal Lowland Peat in the Tropics

Abstract Sago palms (Metroxylon sagu Rottb.) growing on peat soils were found to grow more slowly and to show a lower production than palms growing on mineral soils. This difference was related to the physical and chemical constraints of peat soils, which include low bulk density, high acidity, and low N, P, K, Ca, Zn, and Cu levels. In coastal lowland peat soils, the distance from the sea has been found to be an important determinant of soil elemental composition. We predicted that a sufficient supply of N at the rosette stage would improve sago palm growth and that the availability of N in soil to which controlled release N fertilizer was applied might be higher than that in soil treated with soluble fertilizer. To investigate the changes in the nutrient composition of peat soils at various distances from the sea and the effect on sago palm growth, we studied sago palm areas in Indonesia and Malaysia. To observe the influence of N on the growth performance, we also conducted a fertilizer experiment on coastal lowland peat soil in Indonesia. Distance from the sea had no significant effect on the cation concentration in the soil solution (with the exception of Mg) or on the levels of soil-exchangeable cations. No significant differences were observed between the concentrations of exchangeable cations in surface peat soils and those in mature leaves. However, the concentrations of K, Na, and Ca in mature leaves increased significantly with their concentrations in the soil solution. This finding implies that the concentrations of cations in sago palm leaves depend directly on the concentrations of cations in the soil solution. No significant effect of N fertilizers on plant height and leaf formation was observed. N fertilizers applied twice a year did not affect appreciably the foliar concentration of N determined in December 1998 (5 months after the initial application) and December 1999. In June 2000, we detected a significantly higher concentration of N (p < 0.01) in young leaves of the palms treated with LP-100 or urea than in control leaves. However, no significant difference was detected between the LP-100 and urea treatments in the concentration of N in both mature and young leaves. This finding indicated that the concentration of N in sago palm leaves increased with the level of soil-applied N, regardless of whether N was applied as controlled release fertilizer or in the soluble form. We anticipate that a significant difference in the effects of these N fertilizers may occur during the next rainy season, when there should be a considerable loss of soluble N.

Effect of volatile fatty acids on seedling growth of anoxia-tolerant rice (Oryza sativa L.) genotypes

Abstract Some of the rice genotypes were selected as anoxia-tolerant. But when seeded directly in lowland soil, the seedling establishment of these genotypes varied with the locations. It was assumed that volatile fatty acids (VFA) like acetic, propionic, or butyric acid might be one of the factors that affected this phenomenon along with the pH level. Very specific data related to the anoxiatolerant genotypes, namely VFA and pH interaction, should be analyzed to develop a variety or relevant cultural practice for direct seeding lowland culture. Therefore three in vitro studies were conducted to observe the effect of VFA on seedling growth of five anoxia-tolerant rice genotypes (IR41996-50-21-3, IR50363-61-1-2-2, BR736-20-3-1, RP1669-1529-4254, and Haenuki) under hypoxic conditions and two pH regimes of 5 and 7. The concentrations used for acetic acid were 0, 4, 8, and 12 mM, for propionic acid 0, 1, 2, and 3 mM, and for butyric acid 0, 2, 4, and 6 mM. The solutions for seedling growth were changed every 2 d to minimize the fluctuation of the pH level. Seedlings were grown in a sealed test tube at 30°C for 7 d in the dark. The nature and extent of the genotype response varied with the types of VFA, their concentrations and the pH levels. Based on the survival trend of the first leaf five genotypes were divided into three groups for each VFA separately. First leaf survival was not affected either by the acid concentration or by the pH up to 4 mM in the case of acetic acid and 2 mM in the case of butyric acid for all the groups. Propionic acid, which was assumed to be the most toxic affected, group I (IR50363-61-1-22 and Haenuki) and group III (RP1669-1529-4254) genotypes at around 1 mM. But the mere presence of this acid affected the first leaf survival of group II (BR736-20-3-1) genotype. The change of pH from 5 to 7 led to the increase of the percentage of first leaf survival for some genotypes at higher acid concentrations. However, irrespective of the pH values (5 or 7), genotypes with a high first leaf survival at high acid concentrations were also observed. The estimated concentration of the VFA required for 80% survival of the first leaf depended on the VFA itself and pH level. Seedling parameters were also influenced by pH 7 at higher VFA concentrations.

Kinetic Parameters of Gross N Mineralization of Peat Soils as Related to the Composition of Soil Organic Matter

Peat land has been considered as an alternative type of land for agricultural development especially in the tropics. In the present study, the N-supplying capacity, one of the most important soil properties in terms of crop production, of peat soils was examined. Ten peat soil samples were collected from Indonesia, Malaysia, and Japan. Gross N mineralization in the soil samples was estimated using a zero-order model, and kinetic parameters of mineralization were determined using a simple type model. Soil organic matter composition was investigated using 13C CPMAS NMR. Mineralization potential (N 0), apparent activation energy (E a), and mineralization rate constant (k) ranged between 571–2,445 mg kg−1, 281–8,181 J mol−1, and 0.009–0.020 d−1, respectively. Although none of the parameters showed a significant correlation with the soil C/N ratio, a negative correlation was observed between the k value and the ratio of the proportion of alkyl C in total C to that of O-alkyl C estimated by 13C CPMAS NMR. The latter suggested that the k values were higher in the peat soils relatively rich in readily decomposable organic matter including carbohydrates.

Water uptake under water stress at panicle initiation stage in upland rice as affected by previous soil water regimes

Abstract Under water stress conditions, water uptake from the deep soil layers is a key trait for drought avoidance in upland rice (Oryza sativa L.). In this study, upland rice subjected to different soil water regimes during the vegetative growth (low: − 0.20 to − 0.03 MPa and high: − 0.09 to − 0.03 MPa soil matric potential (\g4s) was investigated to evaluate the daily plant water uptake of the root systems under short-term soil water stress at the panicle initiation stage, by characterizing the distribution of the root length and changes in the water extraction per unit root length q (cm2 d−1) in different soil layers in a column experiment. Irrigation was applied to set the \g4s at − 0.04 to − 0.03 MPa at a 0 −20 cm depth and − 0.03 to − 0.02 MPa in the layers below a depth of 20 cm in both soil water regimes just before the imposition of the water stress treatment. In both soil water regimes, daily plant water uptake decreased continuously during the stress period, while the leaf water potential decreased substantially. During the 0–2 d period after the last irrigation (DALI), the water uptake rate in the 0–20 cm layer was the largest among the soil layers and coincided with the largest root length in this layer. Subsequently, the water uptake rate in the layers below a depth of 20 cm increased temporarily and then decreased rapidly as \g4s decreased, while the water uptake rate at a 0–20 cm depth decreased monotonically. The q value responded to a decrease in \g4s differently depending on the layers in both soil water regimes. In the 0–20 cm layer, the q value decreased continuously with the decrease in \g4s. On the other hand, the q value in the layers below a depth of 20 cm increased with the decrease in \g4s from the range of − 0.03 to − 0.02 to the range of − 0.05 to − 0.04 MPa. However, as the \g4s decreased to below − 0.05 MPa, the q value in the layers below a depth of 20 cm decreased to a larger extent than in the 0–20 cm layer, reflecting the limited root water extraction ability in those layers as water stress developed, irrespective of the soil water regimes. The root length in the 20–40 cm layer increased in the low soil water regime due to the stimulation of the branching of fine and medium roots (42–220 μm). Consequently, the water uptake rate in the 20–40 cm layer was larger in the low soil water regime, which contributed to a larger daily plant water uptake at the beginning of the stress period. During the latter stress period, daily plant water uptake decreased rapidly in both soil water regimes

Fate of basal N and growth of crops cultivated under cassava-based intercropping system with reference to K application rate

Abstract Cassava is the fourth most important staple food crop in Asia and main crop in the cropping systems used in upland areas. Among staple crops, cassava most abundantly absorbs potassium (K), suggesting that a nutrient disorder might occur among the intercrops. A nutrient disorder in intercrops may affect the fate of applied nitrogen (N) through the growth of intercrops. Strong K-absorption ability of cassava can be potentially antagonistic to other crops. If so, when the soil K level is critical in an intercropping system, K application may result in increased yield through mitigation of the K antagonism among intercrops, accompanied with nutrition improvement of other nutrients. We conducted a field experiment to evaluate the growth of crops and the fate of N fertilizer with reference to the application rate of K in a cassava-based cropping system in South Sumatra. The results obtained were as follows: 1) The dry weight values and yield of cassava, upland rice, and corn without K application were lower than those with K application treatment. However, no significant differences in the dry weight and yield of these crops were observed between K application treatments of standard and double dose. 2) The recovery rate of basal N by upland rice and cassava was positively related to the yield of each crop. Amount of immobilized N in soil applied to upland rice was not affected by the application rate of K. 3) Total recovery rate of basal N applied to upland rice was 2 times higher in the K application treatment than without K application treatment. It appears that K application alleviated the N pollution problem by inducing a high uptake rate of N fertilizer by crops.

Effect of slag silicate fertilizer on dissolved silicon in soil solution based on the chemical properties of Gleysols

Increasing the silicon (Si) supply in soil solution enhances Si uptake by rice plants (Oryza sativa L.). In this study, we evaluated soil factors associated with the effects of slag silicate fertilizer (SSF) application on Si supply in soil solution. Nine Gleysols with a wide range of chemical properties were incubated with (+Fertilizer) or without (−Fertilizer) SSF for 71 days under submerged conditions, and the amount of dissolved Si, pH, and calcium (Ca) concentration in the soil solutions were determined. The amount of dissolved Si derived from SSF application (Sidff) was estimated using the subtraction method, and a correlation analysis was performed between the Sidff and chemical properties of air-dried soil or the soil solution obtained from the incubation experiment. The percentage of dissolved Sidff from 0.5 N hydrochloric acid (HCl)-soluble Si in the SSF varied from 15 to 67% among different soils, suggesting that the effect of SSF on Si supply in the soil solution varied among Gleysols. Dissolved Sidff was negatively correlated with the mean soil solution pH (P < 0.001) and Ca concentration (P < 0.05) for +Fertilizer samples during the incubation experiment, soil pH after incubation under submerged conditions (P < 0.001), soil Si adsorption capacity (P < 0.001), acid oxalate extractable iron (P < 0.001) and acid oxalate extractable manganese (P < 0.005), and indicators of soil Si availability (P < 0.05). These results suggested that the effects of SSF on Si supply in solution were affected by Si dissolution from the applied SSF and the Si adsorption capacity of the soil.