MINERAL COMPOSITION OF CROPS / 



Table 2. — Composition of dry matter in vegetation from Armoedsvlakte veld with 

 special reference to phosphorus 



[Theiler, Green, and du Toit (554)] 





Composition of dry matter 



Date 



Crude 

 protein 



Ether 

 extract 



N-free 

 extract 



Crude 

 fiber 



P 



Estimated 



energy 



value 



(starch = 



100) 



Ratio of 



starch 



equivalent 



toP 



Nov. 10, 1919 



Percent 

 19.4 

 14.3 

 13.8 

 7.2 

 4.9 

 4.1 

 4.0 



Percent 

 5.5 

 5.6 

 5.5 

 3.4 

 2.4 

 2.2 

 2.0 



Percent 

 41.0 

 46.8 

 48.0 

 49.8 

 51.6 

 52.9 

 53.7 



Percent 

 22.5 

 25.6 

 25.0 

 33.7 

 35.0 

 34.9 

 33.1 



Percent 

 0.26 

 .14 

 .10 

 .10 

 .05 

 .03 

 .04 



56 



100 • 46 



Dec. 8, 1919 





Jan. 15, 1920 



52 



100-0 19 



Mar. 4, 1920 





Apr. 19, 1920 . 



32 



~~ _ 25~ 



100 -0 16 



May 11, 1920 





June 8, 1920 



100*0 16 







It is stated that except for the very early grass this veld is deficient 

 in phosphorus as well as protein and other desirable constituents all 

 the year round. That this deficiency may be due to the unavailability 

 rather than to a deficiency of phosphorus in this soil is apparent from 

 the fact that the available P 2 5 in the soil is reported to vary from 

 0.0005 to 0.001 percent as compared with a total P 2 5 content of 0.03 

 to 0.12 percent. These authors cite another soil in the same area 

 that contains 0.009 percent of available P 2 5 and that is said to sup- 

 port a pasture that will maintain healthy cows. 



The Armoedsvlakte soil is described as a shallow soil, varying from 

 dolomitic outcrop to a few feet of leached material. According to the 

 extent of leaching it varies from a heavy dolomitic loam to a sandy soil 

 containing very little carbonate, although still alkaline. 



More detailed descriptions of soil characteristics, particularly parent 

 material, as related to the occurrence of bone diseases in animals have 

 been made in New Zealand than in any other locality. The earliest 

 reference by Reid and Aston (479) in 1910 cites this abnormal condi- 

 tion among pastured animals as being the result of "an excess of 

 organic matter and a deficiency of salts in the soil upon which the 

 animals were depastured [sic]." 



The interest in soils probably arose from the observation that 

 adjacent pastures often had quite different effects on the health of 

 the animal. Thus, Aston (33) in his study of the occurrence of osteo- 

 malacia in the Wairarapa district observed, in 1930: 



The district is a very large one, in which, while it contains the most phosphorus- 

 deficient pastures yet met with in New Zealand, certain areas afford soils of great 

 fertility and pastures of high nutrient value. The evidence of the relationship 

 between soils and animal health is convincing and continuous from the soil, the 

 pasture, and to the animal. 



In a further investigation of the soil characteristics in relation to 

 the occurrence of osteomalacia in the Wairarapa district, no definite 

 relationship between soil structure and the occurrence of disease was 

 noted, for it was stated in 1931 by Aston and others (34)'. 



The soil-analyses reveal no soil of excessively course nature, such as pumice, 

 sandy silts or even the coastal dune sands, so that from a mechanical point of 

 view the soils involved show no inherent structural defect. The finest textured 

 soils on which the disease occurs are silt clays, and the coarsest are fine sandy 

 loams. 



