All samples were air-dried and sieved to pass through 2 mm mesh.
Equal amounts of soil from each of the 3 replicate mini-plots were then combined, mixed thoroughly and sieved (mesh-width 3 mm) to remove large particles.
Samples were sieved prior to testing to remove organic debris.
Soil was sieved to 2 mm to ensure homogeneity.
The sand was sieved and washed, and the fraction retained between sieves of 160 m and 425 m pore size was used.
Samples were sieved and sorted to separate plant debris from aphids.
The aphid suspension was sieved and sorted to remove plant debris.
Thereafter, they were washed and sieved through a 0.5 cm-wide mesh to retain the coarse fraction.
