A greenhouse experiment was conducted on two soils of different texture, Tebuk sandy clay and sandy mine tailings. They were treated with different rates of coal fly ash (0, 10, 20, 40, 80 and 160 Mg ha-1) and the uptake of B, Cu, Fe, Mn and Zn by spinach grown in these soils were determined at six weeks growth The experimental set-up hosen for this study was a factorial 2 (different soil textures) × 6 (six rates of fly ash application) arranged in completely randomized design with 4 replications. Application of fly ash increased the pH and EC of the soils Tissue uptake of B, Cu, Fe, Mn and Zn and plant dry matter weight were influenced by fly ash application rates and soil texture type. Boron uptake increased while Cu, Fe, Mn and Zn uptake decreased with increases in addition of fly ash to the soils The highest spinach dry weight was obtained with the application of 20 Mg ha-1 for the Tebuk soil and 40 Mg ha-1 for the sandy mine tailings.
Keywords: Coal fly ash, micronutrients uptake, spinach (A. viridis)
This paper presents the results of a detailed study on Al-for-Fe substitution in goethite on a number of soils at different weathering stages, derived from mafic rocks The least weathered soil (Luvisol) has low iron oxide contents and a smectitic clay mineralogy, while the most weathered soil materials are kaolinitic and rich in non-s1llcate iron. Al-for-Fe substitution in goethite was determined by combining the results obtained by different techniques. (1) selective dissolution by DCB and ammonium oxalate, (2) Mössbauer spectroscopy, (3) thermograv1metrlc analysis, and (4) XRD on NaOH treated samples. A clear increase in Al-for-Fe substitution in goethite is observed with increasing weathering The values obtained by XRD on NaOH treated samples are, however, somewhat higher than those calculated through the combination of methods (1) and (2). This suggests a substantial Fe substitution in kaolinite and/or a dissolution of part of the poorly crystallized goethite by the NaOH treatment, recrystallizing as goethite with a better crystallinity.
Keywords: Al-for-Fe substitution, geothite, Mössbauer, weathering
Pineapple residue in Malaysia is usually burnt. The need for sustainable agricultural development coupled with the 1997 haze problem in Southeast Asia has led to the calls for “zero burning”. A study was initiated at Simpang Renggam Pineapple Estate, Johore to quantify P and K uptake in pineapple parts and to also compare the efficiency of P and K uptake for burn and no-burn practices. At maturity (sixteen months after planting), three plants were sampled from each treatment and partitioned into roots, stem, leaves, fruit, peduncle and crown, and their dry weight, P and K concerntrations determined. Irrespective of treatment difference, P uptake was highest in the fruit, followed by the leaves, stem, crown and roots. The order of K was fruit, stem, peduncle, crown and roots. Between 66 and 58% of the total P and K taken up is recycled and the rest (42 and 34%) is lost through harvest. In situ burning of pineapple leaves before planting does not improve P and K uptake and yield. Major difference in P efficiency for butn (51.60%) and no-burn (53.21%) under fertilized was not observed.
Keywords: Nutrient uptake, pineapple residue management, nutrient partitioning, peat, phosphorus, potassium
Conventional methods of land evaluation use. Boolean logic based on crisp sets (yes/no) and strictly defined suitability classes. Boolean logic ignores the continuous nature of soil variation, resulting in a considerable loss of information. Fuzzy set theory, which is a generalization of Boolean algebra to situations where are modelled by entities whose attributes have zones of gradual transitions, rather than sharp boundaries, offers a useful alternative to conventional methodology. The methodology is tested by comparing observed grain maize yields in two counties in China and land indices calculated by fuzzy set theory with those obtained by conventional Boolean methods - maximum limitation method and the parametric approach Although the fuzzy set approach offers the best results, the most critical issue in its application to land suitability assessment remains the choice of membership functions, class centers, cross-over values and weight values.
Keywords: Fuzzy set theory, land evaluation, maize, China
Growing crops under rain shelter requires massive inputs of fertilizers and other agro-biocides. Except for vegetable farming, where crop rotation is practiced, farmers tend to grow the same type of flowers continuously. This has resulted in high amounts of residual fertilizers in the soil In Cameron Highlands, where flower cultivation has been going on for some years, soil salinity can exceed 10 dS m-1. The main salt constituents were Ca2+, K+, Mg2+, Na+, HCO3-, SO42-, Cl-, NO3- and P Elevated levels of heavy metals (Mn, Zn, Cd, As) were also found in there soils. Soil topping and sub-soiling followed by mixing provides a short-term solution Opening up the plastic cover for leaching by rain was also ineffective Soil desalinization by flooding and continuous leaching was proven to be highly effective in reducing soil salinity.
Keywords: Salinization, desalinization, leaching, rainshelter, flower farms
Elimination of the adverse effects of soil acidity through accurate estimates of lime requirement is essential for optimising alfalfa production This study was conducted to (i) evaluate two methods of lime requirement; KCl extractable Al and the New Woodruff Buffer and (ii) determine the effect of lime reaction tune on soil Al audi alfalfa growth two strongly acid surface soils were treated with lime at 0, 0.25, 0.5, 1 and 2 times tile amount of KCI extractable Al plus the quantity of lime estimated by the buffet (defined L0, L0.25, L0.5, L1, L2 and Lw). Alfalfa (Meduago saliva L.) was grown for five successive harvests in a greenhouse on these treated soils. In addition, soils with the same treatments were incubated for 1, 2, 5 and 10 months. Alfalfa yield increased in all harvests with increased lime additions for both soils except in harvest 1where a growth decrease was observed on the treatment based on the buffer. In later harvests, yield depressions occur-red with lower lime treatments, which were attributed to Al toxicity Soil solution data from the incubated soils showed soluble Al was released with longer incubation times. Liming increased cumulative yields or root weight of alfalfa compared to lime applied at twice the extractable Al. Alfalfa yields were more highly correlated with exchangeable Al than soil pH in both soils. This study suggests that lime requirement of acid and poorly buffered Missouri soils may be more accurately estimated by KCl extractable Al rather than the buffer.
Keywords: Lime, acid soil, alfalfa, calcium, aluminum
Incorporation of crop residues in agricultural systems is an important factor in the control of soil fertility and nutrient cycling, and may contribute significant amounts of nitrogen to the succeeding crop. Decomposition and nutrient release from maize residues applied on the soil surface in tubes inserted into the ground was studied during the fallow and growth period of groundnut Dry matter weight (DMW) loss of residues was fast in the initial two weeks. Generally, decomposition is best described using the single exponential model (Wt=Woe-kt) with rate constants (k) of 0.101% week-1 (r2=0.95), and 0.106% week-1 (r2=0.92) with 50% DMW loss at 7.2 and 7.5 weeks in maize plots of chemical fertilizer and in plots with combined chemical fertilizer and chicken manure with residue. Nutrient release was iii the order of (fast to slow) K>N=P> Mg>Ca. Total soil mineral nitrogen (NH4+-N and NO3--N) during residue decomposition showed maximum accumulation (65 ug-1, in the top 0-20 cm) on die 8th week. Residue incorporation slightly increased flesh pod yield and N uptake. Groundnut growth, in terms of dry matter yield and N accumulation, was most active between the 5 th and 9 th weeks after sowing. These results indicate that better synchrony between N release from residue decomposition and uptake by the subsequent crop (groundnut) could occur if the crop was sown between 4 - 8 weeks after returning the previous crop residue to the field.
Keywords: Decomposition, groundnut, maize residues, N uptake
Experiments were conducted to identify the optimum soil composition as a seedling raising medium for a manually operated transplanter. The effects of moisture content and seedling age on rupture strength, soil bearing index and uniformity index of seedling block after being cut from the mat were also investigated. The average values of rupture strength at saturation (45-50%). intermediate (30-35%) and friable range (20-25%) moisture contents were 3.21 N/cm2, 4.21 N/cm2 and 8.25 N/cm2 respectively. The seedling mat with soil composition (80% silty clay loam soil + 10% sand + 10% Cow dung) at a moisture content of 30-35% dry basis, produced the maximum value for soil bearing index (0.84) which was essential for better crop establishment. Green house seedlings at the age of 13 days produced maximum soil bearing index of seedling block and optimum rupture strength of seedling mat. The addition of saw dust to the mat soil decreased soil cohesion and hence decreased soil bearing index of the seedling block.
Keywords: Seedling mat, rupture strength, soil bearing index and uniformity index