摘要:

Carter (3) in 1943 reported the use of a promising new soil amendment and disinfectant composed of a 50–50 mixture of 1–3 diehloropropene and 1–2 dichloropropane (called “D-D mixture” for short). Among the benefits derived from the use of this mixture in plant tests was the control of the root-knot nematode (Heterodera marioni) in heavily infested soil. Since then other investigators at this institute3have verified the effectiveness of D-D as a nematicide.AnomalaandAdoretuslarvae infesting nursery stock in soil have also been shown to be susceptible to water solutions of D-D mixture (4).Because early observations (3) of pineapple plants grown in the field in soil treated with D-D at 150 pounds per acre gave no evidence of benefit from the treatment until more than a year after application, it was thought that the action of this disinfectant was different from that of others, such as chloropicrin, steam, formaldehyde, and calcium cyanide. The early rapid growth of pineapple plants in soil treated with chloropicrin, resulting in a dark green, broad-leaved, soft, succulent type of plant, was shown to be related to the inhibition of nitrification of applied ammonium, which limited these plants to an ammonium nutrition (12). Since the difference in the time of response of pineapple plants to treatment with D-D and with chloropicrin is important, a comparative study of the nitrogen nutrition of pineapple plants grown in soil following treatment with these two disinfectants was undertaken.

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID

摘要:

The discovery that soil colloids are predominately composed of clay minerals has set in motion a number of researches on the chemical and physical properties of specimens of the several recognized types of such minerals. This investigation is concerned with the effect of the mineralogical and chemical nature of colloids on the availability to plants of replaceable calcium.It has been demonstrated that replaceable cations are an important source of plant nutrients, and that plants obtain these nutrients by cation-exchange reactions. The influence of the nature of the soil colloid in these exchange reactions is not well understood, however, and it seems likely that quantitative measurements of this factor will aid in the laboratory evaluation of soil fertility. The object of this investigation was to compare the manner in which different types of colloids release their replaceable Ca to growing plants and to solutions of electrolytes, and to measure the effect of percentage Ca saturation of the various colloids upon the magnitude of this release.

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID

摘要:

Western Oregon has a large quantity of grain straw and the residues from various seed crops and other similar materials of potential value for mulching. Only a small portion of these materials is used for bedding in stables or applied directly to the soil. The burning of stubble and of straw stacks is a common practice. A study to define more accurately the value of such waste products, especially when used as a mulch, should be conducive to their conservation and more effective utilization, particularly since orcharding and small-fruit production in western Oregon lend themselves to mulching practices.These are the considerations that prompted this study to determine the effect of mulching upon the conservation of moisture, the nutrient supply for crop production, and the structure of the soil.

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID

摘要:

The hydrogen-ion concentration of the pedocals was discussed in a previous paper (1). The present paper, which deals with the pedalfers and the soils transitional between the pedocals and the pedalfers, considers only the most important series and the most representative profiles.

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1945

数据来源: OVID