Miscellaneous, 



348 



[October, 1909. 



When new land is opened there is 

 always a large amount of organic matter 

 in the surface soil, the accumulated vege- 

 tation of many years ; under tillage 

 and clean weeding this vegetation dis- 

 appears, decaying and returning to the 

 soil. Most of the nitrogen in a soil is 

 contained in this form, and at the end 

 of three years' cultivation, practically 

 no leaves or sticks are to be found, the 

 greater part of the nitrogen in this 

 organic matter has become available 

 and absorbed. Of the remainder the 

 most of it has been washed deep into the 

 soil, or into the drains and lost from the 

 plantation. 



It is frequently seen in practice that a 

 first year's crop on newly-cleaned land is 

 poor, the reason is usually excess of 

 acidity produced by the decay of vege- 

 tation in absence of air, but after a 

 year's tillage this disappears. 



It would not be advisable to sow 

 green manure plants among a crop 

 planted on newly-cleared land, but it 

 would be very profitable and advisable 

 to sow green manure crops among 

 Coffee, Tea or Rubber which was grow- 

 ing on a nitrogen-poverty, rain-washed 

 soil, having been submitted to heavy 

 tropical rain during half the year and 

 drought during the ooher half, for five 

 or six years ; receiving nothing but a 

 hoeing to promote the rapid decay of 

 the few leaves which fall from the 

 trees occupying the land. 



One of the great advantages of having 

 organic matter (pieces of plants, etc.,) 

 in the soil is that the organic matter 

 enables the soil to retain soluble nitro- 

 gen and moisture and acts like a 

 sponge increasing the power of imbi- 

 bition. 



Take for example the Coffee crop, it is 

 generally accepted that the most critical 

 time is the time of fioweriug (end of 

 October and early November). If the 

 rains are late, much of the flourish is 

 cast and the result is a small crop. 

 This was the case in Nyasaland last 

 rains, and on a well-known estate I saw 

 fully 100 acres with scarcely a berry. 

 If that soil had been green manured in 

 the previous year, it is very probable 

 that the amount of water retained in it 

 by the organic matter (dead leaves 

 branches, etc.,) from a green manure 

 crop, would have been sufficient to 

 enable the Coffee Plants to retain their 

 flourish until the advent of the rains- 



Another point noticeable in the Coffee 

 crop is the damping off or blackening 

 of the primaries. This is usually worst 

 in old trees, and is undoubtedly closely 

 connected with the vitality of the plants. 

 It is generally attributed to thrips, but 



this is wrong ; thrips may cause defoli- 

 ation, but not the blackening so visible 

 on most plantations in the present year. 

 This blackening off is usually worst on 

 heavy soil, and probably is due to lack 

 of aeration at the roots. Green manur- 

 ing also helps to aerate the soil, and this 

 is one of the mechanical effects of supply 

 of organic matter in the soil. 



The blackening of the primaries, and 

 severity of thrips, have much to do 

 with the condition of the plant when 

 attacked ; and if the plants are half 

 starved for lack of nitrogen, or suffo- 

 cated for lack of air at their roots, they 

 succumb much more rapidly. 



Effect of Green Manure on Rubber. 



It is a general idea throughout Nyasa- 

 laud that Ceara Rubber is the crop to 

 grow on all exhausted Coffee planta- 

 tions, but this is a great mistake. 



The reason why the public have 

 arrived at this decision is the rapid 

 growth of the Ceara plant, but in the 

 writer's opinion the more rapid the 

 growth of a crop the greater the neces- 

 sity of having a responsive soil, rich in 

 soluble and available plant-food consti- 

 tuents. 



A soil for a quick-sjrowing crop should 

 contain a high percentage of nitrogen, 

 as nitrogen stimulates growth more 

 than any other constituents of a plant's 

 food. 



In a cloudy temperate country there 

 is danger in having large quantities of 

 nitrogen, as the growing season is short, 

 and nitrogen retards ripening, but with 

 the sun and dry weather of the tropics, 

 nitrogen in large quantities is always 

 beneficial, as it promotes growth and 

 makes the plants more independent of 

 drought. 



In no other country has the writer 

 noticed Ceara Rubber branching so 

 near the ground as in Nyasaland, and 

 this is much more noticeable in Rubber 

 planted in exhausted Coffee estates 

 than in Rubber planted on the river. 

 It seems to the writer that the plants 

 are suffering from lack of sufficient 

 nitrogen and soil drought ; principally 

 through deficient organic matter in the 

 soil, and that they are developing this 

 undesirable habit of low branching in 

 order to shade their roots with their 

 own branches. 



On some of the highland Rubber 

 estates the Ceara in the first year shoots 

 high and spindly into the air in the wet 

 season, in the month of March flowers, 

 and bears fruit in the first year ; when 

 the dry season comes the plant's energy 

 is expended, with the result that it dies 

 back several feet ; at the advent of the 



