June C, 1008 



HORTICULTURE 



751 



The Misuse of Fertilizers and Manures in the Greenhouse 



'I'lic article in HoRTicui.TURE of April 25, 1908, en- 

 titled "Soluble Fertilizers"' was of interest to us, and 

 since our experiments and observations have been for 

 a number ol' years alont;' this line we eoiild not refrain 

 from oll'ering a few suggestions. 



The statement attributed to Dr. (lallowa}- that "full)- 

 as good results could be secured by the use of good com- 

 posts alone as where chemical manures were applied" is 

 in hannony with the views and practices of market 

 gardeners who lia\c gi'own lettuce in the same soil t\)r 

 many years -without using fertilizers. Most market 

 gardeners would not accept commercial fertilizers for 

 greenhouse use if offered to them free of cost, and in 

 this they are wise as more harm than good results from 

 the use of fertilizers in a greenhouse as ordinarily ap- 

 plied. Kot a single winter passes without our receiving 

 at the Experiment Station incjuiries from growers of 

 greenhouse crops concerning certain peculiar diseases 

 and abnormal growths with which they are unfamiliar, 

 and which can be attributed to the injudicious use of 

 fertilizers and manures, and it would seem that this 

 type of injury is on the increase, for during the past 

 winter we liave received more complaints than exov 

 before. 



The effects of over-nuuiuring on crops may he seen in 

 many ways, as is evident from the pathological symp- 

 toms displayed; in short it may be stated that the stim- 

 ulating effects of plant foods are specific as well as 

 manifold. The writer has had occasion to examine a 

 number nf plants with symptoms characteristic of the 

 misuse of fertilizers. We have also applied fertilizers 

 at various times to greenhouse crops with little or no 

 benefit, and as a matter of fact greenhouse soils, when 

 properly prepared, contain a sufficient amount of plant 

 food to carry the crop thi'ougb. There are undoubted- 

 ly instances of fertilizers being applied to bring about 

 certain definite reactions on the part of the plant which 

 would be desirable, but there are many other cases where 

 such reactions would prove undesirable, if not injurious. 

 It is well known that rose-men who prepare their soil 

 according to the standard formula and apply liquid 

 manure throughout the season make a practice of chang- 

 ing the soil each year, and the question naturally arises, 

 "Why do they change the soil?" This question was 

 asked a few years ago in one of the leading florists' 

 journals but none of the replies were satisfactory. Our 

 investigations have shown that the constant applica- 

 tion of manure to soil already well supplied with avail- 

 able plant food renders it unfit for growing roses a sec- 

 ond year. On the othei' liand, horse manure can be 

 applied to lettuce soils every year in liberal quantities, 

 and the longer such soils are used the better they ai'e, 

 showing that there is much difference between the na- 

 ture of the manure and the amount applied, and there 

 is a difference in the manurial requirements of the crop. 



One of the commercial fertilizers which has caused 

 more trouble than any otlie 



soda, but its effects on diHci-ent plants are by no means 

 the same. In some plants it causes a rupturing of the 

 tissue adjacent to the vascular bundles or it may cause 

 a curling or crinkling of the leaf, ami this often results 

 li-iim a distorted growtli of the vascular bundles. These 

 peculiar pathological conditions have been noticed on a 

 number of different plants. In other cases it inhibits 

 root absorption, while transpiration may be active, caus- 

 ing a wilting of the tender parts of the leaves which 

 will eventually turn brown and die (top-burn, tip-burn, 

 sun scorch, etc.). 



A few years ago the writer described a trouble called 

 leaf and stem curl caused by over manuring, and this 

 trouble can easily he produced experimentally and is 

 often seen in greenhouses. It may also be brought 

 about by an excess of nitrate of soda and a too liberal 

 use of hen, pig and cow manure. The use of fertilizers 

 may also force the plants to such an extent that they are 

 rendered susceptible to certain pathological organisms, 

 and they occasionally throw all their energies into the 

 formation of vines and leaves, to the exclusion of flowers 

 and fruit There is a marked difference in the suscepti- 

 liility of different crops to feeding. According to our 

 investigations, the cucumber appears to suffer the most 

 from the misuse of fertilizers and manures, although a 

 soil which has been fertilized to such an extent that it is 

 unsuited to cucumbers will grow a good tomato crop. 



The nornuil requirements of g:-eenhouse plants as re- 

 gards plant food is a subject in need of investigation, 

 and is being studied at the present time by my colleague, 

 Mr. Haskins, whose article entitled "Chemical Study of 

 Some Greenhouse Soils" accompanies this. The writer 

 has observed the effects of over manuring and the inju- 

 dicious iise of fertilizers on the lily, cyclamen, celery, 

 tomato, lettuce, cucumber, soya bean, etc. There are 

 innumerable instances which might be mentioned where 

 abnormal food relations exist which cause various path- 

 ological conditions in the organism, but a discussion of 

 these individual cases would require too much space. It 

 is not our purpose to contend at the present time that 

 commercial fertilizers cannot be used in a greenhouse on 

 certain crops to advantage by the cautious and skilled 

 grower, but we are led to believe from the large number 

 of cases of the misuse of fertilizers and manures which 

 are constantly being brought to our attention that it is 

 better for greenhouse men to follow the advice given in 

 Bulletin >.'o. 183 of the Massachusetts Agricultural Ex- 

 periment Station, namely: 



"Unless one has an extended knowledge of soil fer- 

 tility, it is best to avoid the use of all commercial fer- 

 tilizers in greenhouse culture. Greenhouse soils are as 

 a rule provided with so much plant food that the addi- 

 tion of fei'tilizers is not absolutely necessary, and the 

 formulas given for outdoor crops cannot be followed. 

 If it is desired to use fertilizers on greenhouse crops, 

 consult station or other authorities familiar with the 

 subject of soil fertility." 



i)i 



T in greenhouses is nitrate of " Amherst, Mass. 



