188 EFFECT OF MONTHLY CUTS ON CHEMICAL COMPOSITION [Vol. XXIII, Part III,
RESULTS AND DISCUSSION
General
Tables I-XIII give the dates of sampling and results of analysis. A general
idea about the chemical nature and nutrient contents of different species of grasses
studied under monthly system of cutting, can be had from the average composition
of all these grasses during the experimental period of May to the end of October
1949. The average composition is as follows:
Crude protein 7.82 per cent; true protein 7.07 per cent; ether extract 3.36
per cent; crude fibre 28.53 per cent; nitrogen-free-extract 46.03 per cent; crude-
ash 14.26 per cent; silica-free-ash 4.72 per cent; silica and insoluble residue 9.54
per cent; lime (CaO) 0.93 per cent; phosphoric acid (P 2 O 5 ) 0.68 per cent.
A comparison of different species can be made by comparing their average
contents of various constituents during this experimental period. Average contents
of crude fibre, crude protein, lime and phosphoric acid of all these grasses are plotted
in Fig. I. Out of all these grasses Themeda trimula gives the highest average crude
protein content.
Seasonal variation of chemical composition
The general trend of variations in. various chemical constituents is shown by the
monthly averages of different constituents of all the grasses. The variations in the
more important constituents namely, phosphoric acid, lime, crude protein, crude
fibre and original moisture as also in lime/phosphoric acid ratio and yield of green
matter for each cutting are indicated in Fig. II. It shows that the variations in
moisture, crude protein and phosphoric acid were similar, while lime, crude fibre
varied inversely with each of the above mentioned constituents. The data further
show that crude ash, ether extract also tended to follow crude protein quite consis-
tantly, while nitrogen-free-extract was correlated with crude fibre.
A further comparison of the average data with those for individual species
shows that there was a good deal of similarity in the changes occurring in the chemical
composition of each of the ten species during the whole of the investigation. This
similiarity was by no means without exceptions and differences did occur in certain
constituents.
Yield of green matter
Table II shows the yield of green matter obtained for each cutting for different
species of grasses. It is seen that the maximum yield in most of the grasses was
obtained in the first cutting, which represented accumulated spring growth. After
this the yield continuously decreased wth each successive cut upto the beginning of
July, i.e., the third cut. With the incidence of heavy rainfall during July which
resulted in favourable soil humidity and favourable temperature condition, the
plants showed vigorous growth. The result was that the yield of green matter of
samples increased considerably and in some cases was even higher than that in first
cutting. Thus in case of Themeda trimula, samples collected during this period on
31 July recorded 14.5 lb. of green matter against 10 lb. in the first cutting. With
the approach of dry weather yield again successively fell till the end of the investi-
gation when the amounts of green matter obtained became very small. This