It has also been observed that too heavy nitrogenous manuring stimulates and prolongs the growing period of the wheat; flowering is retarded, and thus there is a greater opportunity for infection to take place.
The average results show that, under all conditions of manuring - excepting with farmyard manure - the produce was less over the later than over the earlier periods of the experiments, an effect partly due to the seasons.
Lime also assists in the decomposition of the organic matter or humus in the soil and promotes nitrification; hence it is of great value after green manuring or where the land contains much humus from the addition of bulky manures such as farm-yard dung.
If one condition is more necessary than another for good crops it is a suitable supply of water, for no amount of manuring or other treatment of the soil will make up for a deficient rainfall.
The exhaustion of the soil induced by both barley and wheat is, however, characteristically that of available nitrogen; and when, under the ordinary conditions of manuring and cropping, artificial manure is still required, nitrogenous manures are, as a rule, necessary for both crops, and, for the spring-sown barley, superphosphate also.
The first Awe work, written by James Donaldson, was printed in culture in 1697, under the title of Husbandry Anatomized; or, Scotland an Inquiry into the Present Manner of Tilling and in the 18th Manuring the Ground in Scotland.
Thousands of square miles in Lower Bengal annually receive a top-dressing of virgin soil from the Himalayas, - a system of natural manuring which renders elaborate tillage a waste of labour, and defies the utmost power of over-cropping to exhaust its fertility.
The roots were grown under exactly the same cultivation and conditions as a crop of mangel-wurzel - that is to say, they had the ordinary cultivation and manuring of the usual root crops.
But it gave some impetus to the practice of green manuring with leguminous crops, which are equally capable with such a crop as mustard of enriching the soil in humus, whilst in addition they bring into the soil from the atmosphere a quantity of nitrogen available for the use of subsequent crops of any kind.
It is true that on the continent extracted meal, especially rape meal from good Indian seed and palm kernel meal, are somewhat largely used as focd for cattle in admixture with press cakes, but in England no extracted meal is used for feeding cattle, but finds its proper use in manuring the land.