Evaluation of Soil Aggregate Stability under Long Term Land Management System

Abstract

The influence of land management on soil structural stability of National Animal Production Research Institute (NAPRI) farm Shika Zaria in Northern ecological zone of Nigeria was studied. Soil samples were collected from depth of 0-15 cm in fields under three perennial pasture fields not subjected to tillage for over 20 years since establishment using an adjacent continuously cultivated field as reference which has also been under cultivation for over 20 years. The long-term field experiment had four treatments: Three perennial pasture Digit grass “Digitaria smutsii’’, Signal grass “Bracheria decumbens’’, Gamba grass “Andropogon gayanus’’ fields and a continuously cultivated field with 12 samples collected from each plot. The highest dry aggregate stability means 47.40, 42.20, and 38.60 were observed under the perennial grasses land management in the 2-5mm aggregate class. The highest water stable aggregate stability means was also observed under the three perennial pastures following the same trend B.D>A.G>D.S 36.02, 35.18, and 33.68 as observed dry aggregate stability mean values in the 2-5 mm aggregate class range. The land management system under the Bracheria decumbens has 2.07, 0.99 as the highest values for dry mean weight diameter, wet geometric mean diameter, while 0.57 and 1.00 were respectively observed as the highest value for wet mean weight diameter and dry geometric mean diameter under the Digitaria smutsii land management system. Fields under the pasture grasses are higher in organic matter and total nitrogen. The highest C/N ratio value of 1:7.9 was also observed under the pasture grasses fields. The data obtained from the experiment showed that land management under pasture grasses increases the organic matter content, total nitrogen content and consequently increases the structural stability of the soil on long-term basis.