185 



HOEINa AND WATERING. 



Hoeing is one of the much-neglected operations of which few liave considered the 

 value, and to keep down weeds is generally the sole ohject of using the hoe. 

 Certainly that is a good object, and if these observations quicken the vigilance of 

 gardeners who are a wee bit careless upon the growth of groundsel, couch, and 

 bind-weed, and other rampant weeds among their crops, it will serve one good 

 purpose. But it must liave frequently come under the notice of practical men that 

 a piece of cabbage or cauliflower frequently hoed between, even to tlie extent of 

 working the instrument very near their roots, always grow to finer proportions than 

 similar breadths left to take care of themselves, with the ground trodden between 

 to the hardness of a Babylonian brick, " to keep the moisture in and the heat out." 

 In such a case it is made evident that there is a virtue in the hoe beyond the 

 killing of weeds that rob away the nourishment required by the crop ; and if the 

 problem of their well-doing is to be solved by observation, it must be at daybreak, 

 when every leaf is loaded with dew. Then it will be seen that ground recently 

 hoed or pointed over with a small fork is uniformly moist, while hard ground 

 adjoining the same plot is almost as dry as during the heat of a sunny day. The 

 solution is simple enough. The rough open surface absorbs a vast amount of dew, 

 not simply because it is broken, but because it presents a greater extent of radiating 

 surfaces, for the deposition of dew depends on the radiation of heat at the imme- 

 diate surface, and the subsoil need not and will not be colder than the subsoil of 

 hard ground, although it has a greater power of surface radiation. In fact, ground 

 frequently hoed becomes warmer from its more ready absorption and conduction 

 downwards of solar heat, so that the roots of the plants are kept warmer and moister 

 in broken ground than in close hard ground, and therefore the vigorous growth of 

 vegetation is promoted. M. Duchaitre has made systematic inquiries on the depo- 

 sition and effect of dew upon plants, and his conclusions are reported in the 

 " Annales des Sciences Naturelles." In the conclusions there is nothing new. We 

 have ourselves frequently indicated to gardeners that the chief benefit of dew to 

 plants arose through its absorption by the soil for the nourishment of their roots. 



M. Duchartre's experiments show that if tbe dew is allowed to settle on the 

 leaves of plants, and not on the soil in which tbeir roots are, they gain nothing in 

 weight, whereas, when the dew is allowed lo condense on the soil, tliey gain con- 

 siderably. A plant weighing 966'50 grammes was so placed that the soil in the pot 

 had the full influence of the dew, and it had gained in weight, when the dew was 

 removed from the leaves, 13 grammes. Another weighing 1034'25 grammes, gained 

 6'90 grammes. In other experiments, where the soil in the pots was hermetically 

 sealed, there was not only no grain of weight by the dew, but a positive loss, which 

 goes very far to prove that plants do not absorb much moi.siture by their leaf surfaces, 

 and may perhaps give a new turn to our ideas on syringing. But let that pass, we 

 will not throw away the syringe yet awhile. Plants with hard waxy leaves, such 

 as Veronica Lindleyana, certainly do not absorb much, but they need to be kept 

 clean ; and plants with porous leaves, like the vine, do absorb largely, and may be 

 kept alive for some time with the roots dried up, if the leaves are frequently wetted. 

 But the hoeing is the matter we wish our readers to think about and act upon. 

 The hoe is an irrigator of as much value to the English gardener as the Shadoof is 

 to the wretched cultivator of millet on the banks of the Zab or Tigris, and where 

 people are wasting their strength in conveying hogsheads of water which are often 

 more harm than good, the labour might in most cases be saved, the ground kept 

 clean at the same time, and the plants encouraged to push their roots about in 

 search for nourishment by the use of the hoe, and the hoe alone. Take notice of a 

 rhubarb leaf ; the midrib forms a depressed groove, and the leaf slopes up on each 

 side of it, somewhat in the fashion of the two sides of a wooden water-shoot. The 

 upper surface of the leaf-stalk is channelled too, and all night long the leaf distils 

 dew from the atmosphere, the water trickles to the midrib, and thence finds its way 

 by the channel of the stalk direct to the heart of the plant, for the benefit of its roots 

 and rising leaves. This is the way nature makes almost every plant its own 

 irrigator ; we must co-operate with nature, and by the use of the hoe assist the soil 

 alsa to drink freely of the dew of lieaveu, that we may enjoy thereby the fatness of 

 the earth. 



