April, 1909.] 



377 



Miscellaneous, 



Special manures are divided into (1) 

 nitrogenous, (2) phosphoric, (3) potassic, 

 and (4) calcareous. 



Examples of General Manures.— (a) 

 Cowdung, (6) castor cake, (c) rape cake, 

 mustard cake, gingelly cake, (rf) Green 

 manuring. Examples of special man- 

 ures :— 



1. Nitrogenous— (a) saltpetre (Indian)' 

 (&) sulphate of ammonia, 2. Phosphatic 

 —(a) bonemeal, (b) superphosphate. (3) 

 Potassic (a) wood ashes, (&) saltpetre 

 (Indian). 4. Calcaieous (a) bones, (b) 

 ground kankar, (c) lime. 



A general manure contains its plant 

 food in an insoluble form, and before 

 plants can make use of these insoluble 

 forms they must first be converted into 

 a soluble state. This takes time and 

 requires the requisite amount of air, 

 moisture and heat before the changes 

 can take place. These changes, however, 

 take place very rapidly in Bengal, where 

 conditions tor these are at a maximum. 



The very fact of the ingredients of 

 plant food being in an insoluble state 

 in a general manure is of extreme im- 

 portance, as will be seen from the next 

 paragraph. 



A special manure contains its ingre- 

 dients generally in a soluble state, and 

 this is where the danger comes in 

 when recommending special manures. 

 For example, the nitrogen in saltpetre 

 and sulphate of ammonia and the 

 potash in saltpetre are soluble in water. 

 What would be the use of applying 

 these manures in June, July, August 

 and September in Bengal "when the 

 land goes under water? These are 

 the most costly manures, and it would 

 be simply waste of money to apply 

 them in these months as they would 

 be washed into the drainage channels. 

 Similarly in the rabi season, irrigation 

 is necessary and extreme personal care 

 will be required to prevent the manure 

 being washed away. The phosphoric 

 acid in bone-meal is in an insoluble condi- 

 tion and is not soluble in water, so 

 there is not so much danger of loss 

 with this manure as with the others. 

 Superphosphate and wood ashes are not 

 so soluble and are therefore not so 

 dangerous as saltpetre to deal with 

 but they are more soluble than bone 

 meal. 



Accordingly, extreme personal care is 

 requisite in the use of artificial manures ; 

 and unless this can be given we recom- 

 mend them to be left alone. 



There is an art in irrigation, and where 

 manures are applied this art requires 

 to be highly developed in order to ob- 

 tain the money value out of the manure. 

 It is no use swilling the crops and 



Hooding the land if the mauures are re- 

 quired to have their full effect. The art 

 is to give sufficient water and no more. 



When the land is covered with water 

 decomposition of manure is reduced to 

 a minimum as air, one of the essentials 

 of decomposition, is excluded, so that 

 there is less fear of loss by flooding 

 and washing away from a general man- 

 ure during the rains. Accordingly, gen- 

 eral manures such as cowdung, castor- 

 cake and green manure is a more safe 

 manure to deal with than one that 

 can be washed into your neighbour's 

 field, and we can recommend them. Also 

 at the end of September, conditions 

 for decomposition of their insoluble 

 portions into a soluble state are at a 

 maximum in Bengal (when the water 

 is below surface level) and the ingredi- 

 ents of plant food become much quicker 

 available than is possible with such 

 mauures in a more temperate climate. 



Cowdung is so quickly decomposed, that 

 so far as we can find out at present, there 

 is no residue left for a second year's 

 crop. Leguminous crops or Dais have 

 a special feature ic that on their roots 

 they have little warts or nodules in 

 which live bacteria that are able to 

 make use of the free nitrogen of the 

 atmosphere and convert it into available 

 plant food for the use of the crop. 

 This causes plant food to be stored up in 

 the soil in the roots of the crop, and 

 when the crop is harvested the roots 

 decompose and give up their store of 

 plant food to the next crop. This is 

 the reason why ever so long a legu- 

 minous crop should occupy the land 

 so as to give the opportunity to the 

 bacteria in the warts on the roots of 

 the leguminous plants to return a 

 little atmospheric nitrogen to the soil 

 Also when green manuring is resorted 

 to a leguminous crop should be taken, as, 

 in addition to the store of organic matter 

 that will be incorporated with the soil, 

 an additional stock of atmospheric 

 nitrogen will be obtained. Hence the 

 reason why we recommend Dhaincha 

 which is a legume. 



After many years of experiment the 

 following manurial applications have 

 been found economical in Bengal, and 

 we give them as a basis on which culti- 

 vators can work :— 



PAUDY-^-a. 50 maunds Cowdung. 



b. Green manuring with 

 Dhaincha. 

 Potato— a. 200 maunds Cowdung, 



b. 20 maunds Castorcake. 

 Jute— a. 100 maunds Cowdung. 



b. 7 maunds Castorcake. 



Sugarcane— 200 maunds Cowdung 

 plus 8 maunds Castorcake. 



