The use of controlled release fertilizer (CRF) has become a new trend to minimize environmental pollution. In this study, urea-kaolinite containing 20 wt% urea after one hour dry grinding was mixed with different concentrations of chitosan as a binder to prepare nitrogen-based CRF. Fourier transform infrared spectroscopy confirmed the hydrogen bonding between urea and kaolinite. Covalent interaction between urea-kaolinite and chitosan make the granules stronger. The nitrogen release was measured in 5 days interval using a diacetylmonoxime calorimetric method at a wavelength of 527 nm. The results illustrated that by increasing the chitosan concentration from 3 to 7.5%, nitrogen release decreased from 41.23 to 25.25% after one day and from 77.31 to 59.27% after 30 days incubation in water. Compressive stress at break tests confirmed that granules with chitosan 6% had the highest resistance and were chosen for ammonia volatilization tests. Ammonia volatilization was carried out using the forced-draft technique for a period of 10 weeks. The results showed that the total amount of ammonia loss for conventional urea fertilizer and urea-kaolinite-chitosan granules was 68.63 and 56.75%, respectively. This controlled release product could be applied in agricultural crop production purpose due to its controlled solubility in the soil, high nutrient use efficiency and potential economic benefits.
Urea-intercalated kaolinite containing 20 wt% urea was granulated and coated with water-based epoxy resin to prepare nitrogen-based controlled release fertiliser (NCRF). The nitrogen release property was studied using UV-Vis spectroscopy through the diacetylmonoxim colorimetric method for different samples of granules of urea-intercalated kaolinite and nonintercalated urea-kaolinite mixture. Also the effect of granules size and different coating thickness on nitrogen release from coated NCRFs was investigated. The results of release experiments revealed that intercalation of urea into kaolinite caused a three times decrease in the nitrogen release compared to non-intercalated sample. Also, by increasing the size of granules and thickness of coating, the nitrogen release ratio from NCRFs decreased. Finally, a glasshouse trial was conducted to evaluate the effect of coated urea-kaolinite compared with a non-coated one and conventional urea fertiliser granules on rice productivity (Variety MR 219). The yield together with some yield component data (filled spikelet, spikelet per panicle, productive tiller) revealed a highly significant and positive response to coated CRF N fertiliser treatment (one time application). Also, the pooled data of the yield and yield component emphasised that the rice crop responded significantly to treatments involving CRF nitrogen fertilisers as compared to others. The maximum grain yield of 28.73 g/pot belongs to coated CRF, medium grain yield of around 21.74 g/pot from the non-CRF N fertilisers plots and the lowest yield was obtained where conventional urea was applied. The other morphological and physiological characters show a similar trend to the yield.
a laboratory of Food Crops, institute of tropical agriculture, Universiti putra malaysia, Serdang, malaysia; b laboratory of plantation Crops, institute of tropical agriculture, Universiti putra malaysia, Serdang, malaysia; c Faculty of agriculture, Department of land management, ABSTRACT A two years field study was conducted to explain the effect of Zn and lime application on morphological characteristics, rice yield and yield components, and more broadly, grains biofortification (Zn and protein content (CP), and amino acid profiles). The lime and Zn interaction increased grains and straw yield more than two times (6.64 ton ha −1 ) compared to the control (3.20 ton ha −1 ). The maximum increase in the Zn content of grain, white rice and bran was obtained about 30% in whole grain, 42% in bran and 56% in white rice. Furthermore, CP increased by about 8% in bran, 12.3% in whole grain, and 27% in white rice compared to control. Also, the Zn and lime application and their interaction were significantly increased the amino acids, especially essential parts.
Materials and methods
Soil selection and physico-chemical analysisA two years experiment was conducted in the acid sulphate soils research field, Kelantan, one of the major rice
Knowledge of zinc (Zn) distribution among various fractions will help to predict the potential of the soil to supply sufficient Zn for crop production. The present study was done to investigate Zn fractions, Zn availability factor (AF) and their relationship with soil properties of Zn-deficient tropical paddy soils. The samples of two soil orders (six soil series) were sequentially extracted with chemical extractants in two different growth stages of rice (maximum tillering and flowering stages). The proportion of Zn fractions extracted at the maximum tillering stage followed the order, water soluble plus exchangeable (WE) < crystalline sesquioxide (Cry) < manganese oxide (MN) < organically bound (Org) < amorphous sesquioxide (Amor) < residual Zn (Res), whereas the order at the flowering stage was as follows: WE < Mn < Cry < Org < Amor < Res. Cation exchange capacity (CEC), clay content and organic carbon (OC) were the most important factors controlling the distribution of Zn in soils. The AF was low in Tok Young (1.79%), high in Telemong (17%) and medium in the rest of soil series (around 8%). A stepwise multiple linear regression and principal component analyses showed that OC, clay content and CEC were the main variables that explained the predictability of Zn fractions. The result of the length of submerging showed that the WE, Org and Cry concentrations decreased, while Amor, MN, and the sum of all Zn fractions increased with increase in the flooding period. The extractability and solidphase fractionation of Zn in two different times of soil sampling showed the importance of timing of Zn fertilizer application and flooding or pre-flooding in Zn availability.
<p>The conventional Boolean logic models of land suitability assessment disregard the continuity concepts of the soil and landscape which might cause inaccurate evaluation and classification. To overcome this uncertainty and consequent constraints, the fuzzy set theories were introduced. Therefore, the current study was undertaken to estimate the optimum soil depth that is used in land suitability evaluation for irrigated rice through the fuzzy sets theory and analytic hierarchy process (fuzzy AHP) in Guilan Province, Iran. The square root and quantitative land suitability evaluation methods were employed to calculate traditional land suitability indices (for depths, 0-25, 0-50, 0-75, and 0-100 cm). Also, fuzzy and fuzzy AHP methods were used to explore new land indices. The Sarma similarity indices were used to compare the results of traditional and fuzzy methods for different soil depths. The results showed that the compatibility percentage between the representative pedons (0-100 cm) and the findings of this research (0-50 and 0-75 cm) were remarkable. Furthermore, the highest compatibility percentage of land suitability class was related to the comparison of these two former depths and 0 to 100 cm depths in each of the two used fuzzy methods. Besides, except for 0-25 cm depths, actual yield revealed a significant and positive correlation with the rest three soil pedon depths. These findings show that considering 0 to 50 cm soil depth might be a relevant alternative as the optimal depth to evaluate land suitability for rice in paddy fields in the Guilan rice-growing area. </p>
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