S5^ Journal of Agriculture. [lo !N[ay, 1910. 



AITROGEN Frek PLxtract. — W.S.B. asks for an explanation of the term 

 ■■ Xitrogen Free Extract.' 



Answer. — It is used to indicate principally the carbo-hydrates in a food- 

 slutt. Carbo-hydrates, in turn, comprise chiefly the starches and sugars, which 

 consist chemically of carbon, hydrogen and oxygen in different jiroportions. 

 These, together with protein and fat, are the jirincijjal nutrient constituents in a 

 food. In most foodstuffs, carbo-hydrates predominate in quantity, and they are 

 considered to be correspondingly less valuable commercially. It is usually 

 reckoned that a given quantity of protein is worth twice as much as the same 

 quantity of carbo-hydrates, and that the fat is worth three times as much. 



■" Carm.ax " Potatoes. — J.M. incjuires as to difference between "'Carman"' 

 l)Otatoes, Nos. i, 2, anfl 3. 



Answer. — There is no potato known as Carman No. 2. The difference between 

 Xos. I and 3 is : — The latter is a heavier yielder with larger tubers, the fdanls 

 are larger and more vigorous, and are regarded as later maturing than No. i, but 

 ihere is very little difference in this respect. 



Seaweed as a Fertilizer. — J.T. writes : — " I have 3 acres of sandy soil which 

 Was, until last year, covered with ti-tree. I have cleared it all, and have since 

 carted 50 loads of seaweed on to it. Is the latter a good manure?" 



Answer. — Seaweed may be used as a fertilizer on sandy soils. As it con- 

 tains aoout 80 per cent, of water, it will not pay to remove it far from the coast. 

 It decomposes rapidly and thus acts at once; but the jjercentage of plant food in 

 seaweed is small, and it would, therefore, be advisable to continue the dressing 

 yearly, if j)Ossible. 



Paspalu.M. — J.M. asks what is the best kind of paspalum for the Cunninghame 

 district. 



Ansciier. — Fasfahim virgatum is recommended. If seed is used it should be 

 sown in seed bed, and when ])lants are strong enough the\- should be transplanted 

 in check rows 3 feet apart, or at the rate of 4,840 j)lants to the acre. January 

 to May is the best time to sow the seed. In your district jjlanting roots is recom- 

 mencled — any lime from April till October. 



W.ATER FOR Irri(;.ation. — S.H.M. asks if brackish water is of any value for 

 irrigation. 



Answer. — Much de])ends upon tlie anioimt of minerals contained. This can 

 only be ascertained bv analyses extending over different jieriofis of flow of stream. 

 Certain soils will benefit bv one or two ap])lications of mineralised water, but will 

 not stand repeated waterings. If only slightly affected, the water may be used 

 jjrovided efficient under drainage is jjrovided. 



Eradicating Thistles. — C.W.C. and M.E.M. in(juire as to best method of 

 eradicating thistles. 



Answer. — (i) The Shore or .Slender Thistle {Cardiiiis fycnocefhaliis, E.) is an 

 annual or biennial, the latter especially if cut or crojiped, so that flowering is pre- 

 vented during the first year. Hoeing to be most effective must be done while the 

 seedlings are young and the cut should be low down below the knot where the first 

 seed leaves are attached. Cutting above this point simjdy makes the plant branch 

 more freely. The rq)ening and spread of seeds from plants which have escajjed 

 the previous treatment should be prevented by hoeing or pulling them out of the 

 ground, piling and burning. Cutting down the plants may merely leave them to 

 grow from the base and ripen seed next year. In all land which can be ploughed 

 this thistle is easily destroyed by thorough and clearly cultivation, stirring the 

 soil as often as any fresh seedlings appear. Rough, rocky, hillv land which cannot 

 be ploughed should be kept under limber, and will then not be liable to tlje incur- 

 sion of weeds which it is not i)rofitable to supjiress on such land. 



(2) Perennial or "Californian" Thistle [Carduus arvensis, L.). — Plough deeply in 

 autumn and spring, raking out the rhizomes after harrowin" and rolling to break the 

 clods. Summer fallow, ploughing when necessary. Next season plant a j^otalo or other 

 root crop which allows working between the rows, after adding 10 to 15 tons ( f 

 farmyard manure per acre. This should be followed by any crop (drilled-maize, 

 cabbage, &c.,) which can be kept clean between the rows, then a grain cro]), after 

 which the land can be seeded down again in grass or clover or both mixed. After 

 this, any thistles reappearing will be from seed blown in from adjoining land or 

 from impure seed. Where there are only a few thick patches, these can be dug 

 deeply and the rhizomes forked out, piled, and burnt, the thinner patches being 

 hand pulled after rain or cut as often as possible. Only continuous and well- 

 directed labour extending over two or three years can clean land of this thistle. 

 Poisons and salts r.re useless for all plants with perennial underground parts. 

 The cost is [irohibitive, since doses are reijuired which spoil the land for other use 

 for some time. 



