In soils of tropical climate regions the high acidity and the presence of exchangeable aluminum (Al), associated to low fertility, are the main restrainting factors for agricultural production. A laboratory experiment was conducted using 26 soils of different Brazilian regions, to investigate soil acidity components, giving emphasis to Al and their relations with chemical properties. The pH cor...

A random partition of the positive integers is called partially exchangeable if for each finite sequence of positive integers n,, ... , nk, the probability that the partition breaks the first n1 + + nk integers into k particular classes, of sizes nl,.. . ., nk in order of their first elements, has the same value p(nl,...,nk) for every possible choice of classes subject to the sizes constraint. ...

The long-term effects of green cane harvesting with trash retention, compared with burning, on soil fertility were evaluated using data from the long-term trash management trial at Mount Edgecombe (BT 1). Total and potentially mineralisable soil N were greater under green cane harvesting than burning in the surface 0-10cm layer of soil. As expected, fertiliser applications induced increases in ...

The rates of extraetíon of Na, K, Mg, Ca, and Al with 1 M NH. NO. from the mineraIand organic-rieh layers of sorne Park Grass (Rothamsted) soils were measured at the pH of the soil. Below pH 3.7 exehangeable Al, deríved from the kineties curve, inereases with decreasing soil pH and is less in the organic-rich Iayer. The sum of the basic exchangeable eations, I;(Na + K + Mg + Ca), increases with...

Three Ohio soils, Hoytville clay, Brookston silty clay loam, and Wooster silt loam located at various branches of the Ohio Agricultural Research and Development Center, were studied. Bulk samples from each horizon were tested for exchangeable basic cations, pH, sulfuric acid extractable potassium (K+), and particle-size distribution. The surface horizons of each soil were characterized by measu...

flood water contains high amount of sediment affecting the fertility of the coarse grain alluvial fans and flood plains through increasing nutrients. in this study, the effects of the flood water spreading on the soil nutrients recovery were investigated during 10 years (2004-2014) at the poldasht flood spreading station of west azarbaijan in iran. flooded three upper strips were selected at th...

the effects of banana continuous cropping on soil quality and chemical properties and crop yield were investigated under continuous cropping for 1, 3, 5, 7, 10, and 15 years in hainan province, china. the results indicated that the contents of total n, total k, available k, nh4-n, exchangeable ca, and available cu tended to increase, while total organic c (toc), available s, and available zn te...