A study of the influence of animal manure and clover on the structural and chemical characteristics and the earthworm activity in a Manawatu soil : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Field Husbandry of the University of New Zealand

Abstract

In view of the increasing emphasis that is being placed on pasture production by the N.Z. farmer, part1cularly in the North Island, a full appreciation of the value of the grazing animal and clover in relation to pasture yield and composition is of prime importance, While knowledge concerning these factors has been steadily increasing over the past decade; due largely to the work of the Grasslands Division, D.S.I.R., little information is available relating to their effects on the soil itself.The object of the present investigation was to elucidate as many of the effects of manure and clover as was practicable using as experimental material certain plots which formed part of a pasture trial being conducted by the Grasslands Division. Accordingly the following aspects were selected for study: (a) the effect on the structural characteristics of the soil (b) the effect on the level of available nutrients in the soil (c) the effect of earthworm activity on the soil

Although it is realized that these effects are not mutually exclusive of one another the results of the investigation are considered separately under these headings for the sake of clarity of presentation. The area concerned consisted of a series of plots laid down in the autumn of 1946 by the "Grasslands" Division to investigate the influence of animal manure and clover on pasture composition and yield. The major treatment involved the comparison of "return" with "no return" of dung and urine on grass swards with and without clover; within these two major treatments, six minor treatments involving various combinations of superphosphate and lime were included. The trial was in duplicate and the six minor treatments arranged in reverse order. Owing to the fact that the experiment was a :Mowing trial" the animal manure required for the treatments was obtained from specially harnessed sheep grazing an adjacent identical experiment being conducted under natural grazing conditions. The manure collected therefrom was added to the plots concerned in the present study, after each mowing, in amounts proportional to the dry matter produced.