MANGANESE TOXICITY AQUTIC SYSTEM : AN IMPACT OF EXCESS MANGANESE IN SOLUTION CULTURE ON PLANT GROWTH

Mn2+ sangat larut di dalam system aquatic dimana prinsip kultur larutan adalah sama dengan system akuatik. Dua set eksperimen mengenai pengaruh konsentrasi Mn2+  di dalam kultur larutan terhadap pertumbuhan tanaman telah dilakukan di rumah kaca University Putra Malaysia, Serdang, Selangor, Malaysia. Studi ini bertujuan untuk mengetahui konsentrasi toksik Mn2+  di dalam kultur larutan pada pertumbuhan tanaman. Sebagai tanaman indicator adalah “vegetable soybean” (Glycine max L.) Pada eksperimen pertama menunjukkan 60 µM Mn berkesan sangat toksik pada pertumbuhan tanaman, sementara pada eksperimen kedua menunjukkan bahwa 7.5 µM adalah optimum. Penurunan berat kering daun, akar dan batang tanaman soybean sangat nyata pada taraf 37.5 µM. Ianya disebabkan oleh pengurangan luas daun dan panjang akar dengan penambahan konsentrasi Mn2+ pada kultur larutan

Changes in chemical properties of an Ultisol as affected by palm oil mill effluent application

An experiment was conducted to determine the effects of palm oil mill effluent (POME) application on soil chemical properties. The POME was incorporated into the top 0-30 cm of Batang Merbau soil, an Ultisol. POME was applied at 0, 5, 10, 20, and 40 t ha-1, both in the presence and absence of 2 t ground magnesian limestone (GML). A succeeding crops of maize and groundnut were planted. The results of the experiment showed that POME application up to the rate of 40 t ha-1 did not significantly change the topsoil pH and exchangeable calcium (Ca), magnesium (Mg), and aluminum (Al). The addition of POME improved the soil fertility, which resulted in an increase of maize yield. The Ca and Mg from the POME accumulated in the topsoil, being held by the negative charge present on the exchange complex. The beneficial effects of POME and/or GML application lasted for about 3 years. The study indicated that application of POME together with GML is a good agronomic option to alleviate soil acidity in Ultisol for maize production

Longevity of ground magnesium limestone applied to an Ultisol

Soils in the upland areas of Malaysia are mostly weathered (Ultisols and Oxisols), having high aluminum (Al), but calcium (Ca) and/or magnesium (Mg) deficient. Magnesium limestone is available in large quantities in Malaysia and is frequently being used to alleviate acidity in the upland soils. This study aimed at assessing the longevity of the limestone applied to an highly weathered acid soil under conditions prevailing in the tropics. The experiment consisted of two phases; in the first phase the plots were treated with various rates of lime, while in the second phase some plots were left as residual treatments. The results of the study showed that an acid Ultisol of Malaysia can be ameliorated by annual limestone application of 1 t ha-1 for maize (Zea mays L.) production. The beneficial effects of liming with ground magnesium limestone (GML) at 4 t ha-1 were observed for about eight years. The critical soil pH and exchangeable Al for maize production were found to be 5 and 0.7 cmol(c)kg-1 soil, respectively. The Ca and Mg from the limestone were mostly found in the topsoils because of the increase in cation exchange capacity (CEC) resulting from the pH increase

Charge characteristics in relation to free iron and organic matter of soils from Bambouto Mountains, Western Cameroon

We have examined the charge characteristics, with special emphasis on the role of free Fe and organic matter, of humid tropical soils from Bambouto Mountains, Western Cameroon. The soils, which are formed from tuff, basalt and trachyte, are dominated by kaolinite and sesquioxides. The mounts of Fe oxides in them increase somewhat with depth. Open 2:1 phyllosilicates are present in trace amounts. The point of zero charge of the variable charge components, pH0, is around 4 in the topsoil (0-20 cm) and around 6 at 100-150 cm depth. In the subsoils, pH0 exceeds soil pH presumably because of large quantities of Fe oxides. Deferration increases both soil pH and pH0, but diminishes the anion exchange capacity. Oxides and oxyhydrates of Fe have positive surface charge, so their removal from the soils would result in overall loss of positive charge. Increases in soil pH would bring about an increase in the cation exchange capacity of the soils. Hence, management practices that reduce soil acidity should reduce loss of essential basic cations via leaching

Nitrogen Management in a Maize-Groundnut Crop Rotation of Humid Tropics: Effect on N2O Emission

Development of appropriate land management techniques to attain sustainability and increase the N use efficiency of crops in the tropics has been gaining momentum. The nitrous oxides (N2Os) affect global climate change and its contribution from N and C management systems is of great significance. Thus, N transformations and N2O emission during maize-groundnut crop rotation managed with various N sources were studied. Accumulation of nitrate (NO3 –) and its disappearance happened immediately after addition of various N sources, showing liming effect. The mineral N retained for 2–4 weeks depending on the type and amount of N application. The chicken manure showed rapid nitrification in the first week after application during the fallow period, leading to a maximum N2O flux of 9889 μg N2O-N m–2 day– 1. The same plots showed a residual effect by emitting the highest N2O (4053 μg N2O-N m–2 day– 1) during maize cultivation supplied with a halfrate of N fertilizer. Application of N fertilizer only or in combination with crop residues exhibited either lowered fluxes or caused a sink during the groundnut and fallow periods due to small availability of substrates and/or low water-filled pore space (<40%). The annual N2O emission ranged from 1.41 to 3.94 kg N2O-N ha–1; the highest was estimated from the chicken manure plus crop residues and half-rate of inorganic N-amended plots. Results indicates a greater influence of chicken manure on the N transformations and thereby N2O emission

IMPROVING FERTILITY OF ACID SULFATE SOIL USING VARIOUS LIME SOURCES FOR RICE GROWN IN MALAYSIA

The main problems of acid sulfate soils are high acidity and Al and/or Fe toxicity to the soil. This problem causes rice root inhibition, hence retard plant nutrient uptake for its growth. Improving these conditions is important; hence, liming seems to be a common practice to ameliorate this soil, especially for rice cultivation. A study was conducted to evaluate the effects of applying ground magnesium limestone (GML), hydrated lime and liquid lime on the growth of rice under glasshouse conditions. MR 219 rice variety was used in this experiment. It was found that the application of 4 t ha-1 of GML had produced the highest rice yield of 8.2 t ha-1 under glasshouse condition. The result showed that as panicle length increase, spikelet per panicle also increases. Relative rice yield is negatively correlated with the soil pH, and this indicates that as soil acidity increase (observed with pH between 2 to 3), the rice yield decreases and vice versa. At harvest, due to liming practices, the soil pH exceeded 6 for all the treatment. It was also observed that as soil exchangeable Ca increase, soil pH also increases. Among the treatment, soil treated with 2 t ha-1 of hydrated lime gave the highest exchangeable Ca in the soil of 11.86 cmolc kg-1 soil with Ca concentration of 0.12% in the root. It was observed that liming increases soil pH and exchangeable cations in the soil. Therefore, liming is essential to ameliorate the acid sulfate soils for rice cultivation

Temporal changes in chemical properties of acid soil profiles treated with magnesium limestone and gypsum

Effects of ground magnesium limestone (GML) and gypsum on the properties of Ultisols at two sites, involving a corn groundnut rotation, were studied over 24 months. GML or gypsum was incorporated into the soils of the Bungor and Rengam Series (Typic Paleudults), at the rates of 0, 0.5, 1.0, 2.0, 4.0, and 8.01 ha to depths of 15 cm (GML and gypsum) and 30 cm (GML). Increases in soil pH and exchangeable Ca and Mg arising from GML application were confined mainly to the zone of incorporation. However, there was a decrease of exchangeable Al at deeper depths. After 15 months, there was a tendency for the pH and exchangeable Ca and Mg on the zone of incorporation to decrease and for the exchangeable Al to increase, effects being the least at the high rates of GML application. There was no significant change in pH or exchangeable Al as a result of gypsum application, but there were increases in exchangeable Ca and extractable SO in both the zone of incorporation and the subsoil. With time, the exchangeable Ca and extractable S0 in the sub-soils were found to increase, but their concentration in the zone of incorporation decreased. The pH of the soil solution of the control treatment was about 4.0, while Al and Mn concentrations were 150 and 50 μM, respectively. At the GML rate of 2.01 ha or less, Al in the soil solution was found to exist in the inorganic monomelic form. Meanwhile, the GML application at the rates > 4 t ha could have resulted in complexation of some of Al. In particular, Al was the dominant Al species at low pH and liming resulted in a decrease of Al species and increase of hydroxyl-Al monomers. GML needed to raise the pH of the soil solution to about 5 was 2.0 t ha; this consequently decreased Al and Mn concentrations to a low level. The application of gypsum resulted in a decrease and an increase of Al and A1SO activities, respectively

Breeding of maize for acid soil tolerance

Maize is one of important crops which is utilized in a wide variety of human food, animal feed and raw materials to industrial product around the world. In the tropics, maize is usually planted in acidic soils and it’s yield is unsatisfactory in the soils. Planting maize hybrid varieties tolerant to acid soils along with the use of sustainable agronomic practices offers an effective strategy for improving maize productivity in acidic soils. This book describes the process to produce and select maize hybrids tolerant to acidic soils. This book covers the heterosis of single cross hybrids and combining ability of their parental inbred lines evaluated in acidic soils, and heritability estimates from the hybrids populations. This book also covers the use of SSR markers to predict heterosis and hybrid performance. It is hoped that the findings from the study may help maize breeders to produce new hybrid varieties having high yielding potential and tolerant to acid soils