Amelia Moyano

Humic fractions and their nitrogen content in semiarid soils of the duero Basin, Spain

Abstract Carbon and nitrogen contents of humic fractions in representative culti‐vated soib of the southern part of Duero Basin, Spain, were examined to obtain information on possible seasonal variations of organic C and N after one year of fallowing. High percentage of humic fraction in the total soil C, comprising 50%, implied a high stability of the soil organic matter. About 50% of total N content in soils was present in humin. The total organic C in these cultivated soils was low (average 0.56%), and the proportional distribution of the different organic fractions in the organic matter remained statistically stable throughout the year. Nearly 100% of soil organic C was in humic forms; however, the extractable humic forms comprised about 42%.

Boro hidrosoluble en suelos del centro‐oeste semiárido de españa y su relación con los parámetros edáficos

Abstract Water soluble boron content was examined in 26 cultivated semiarid soil profiles where symptoms of boron deficiency had been observed at certain periods. Generally, the water soluble boron contents were lower than 0.5 μg g‐1, and only one epipedon had a value above 1.0 μg g‐1. Statistical evaluation of boron content in relation to other edaphic parameters showed that boron was related to soil pH, available Ca and available K in surface and subsurface horizons. The presence of organic matter had a slight influence on boron content. These relationships did not seem to be sufficient to account for the deficiency symptoms. The symptoms were suspected to be associated with hydric stress.