EFFECT OF IRRIGATED CROP ROTATIONS ON YIELD AND SOIL FERTILITY

1964 ◽  
Vol 44 (2) ◽  
pp. 139-144 ◽  
Author(s):  
S. Dubetz ◽  
K. W. Hill

Crop yields and soil analyses were compared from three 4-year, two 5-year, and two 7-year rotations. The yields of potatoes from the seven rotations were not significantly different. Barley was grown in six rotations and the yields from these were not significantly different. The yield of sugar beets from the one rotation that did not receive any manure was significantly lower than those from the other six rotations. In the rotation in which sweet corn followed sweet clover green manure the yields were significantly lower than those from the other six rotations, where the corn followed sugar beets. This presumably was a result of the phytotoxicity of the decomposing clover. Good husbandry practices such as manure and fertilizer application evidently overshadow the effect of rotations on the yields of irrigated crops. The organic matter and nitrogen of the surface 6 in. of soil were maintained in the rotations that included 3 years of alfalfa or alfalfa–brome mixture. These soil constituents were not maintained with a single year of alfalfa or with a partial green manure crop.

1986 ◽  
Vol 66 (2) ◽  
pp. 273-285 ◽  
Author(s):  
J. F. DORMAAR ◽  
C. W. LINDWALL ◽  
G. C. KOZUB

A field was artificially eroded by levelling in 1957 and then continuously cropped to barley for 7 yr. Subsequently, a wheat-fallow experiment was conducted from 1965 to 1979 to determine the effects of four fertilizer treatments and green manure (yellow sweet clover) on restoring the productivity to soil that had been "eroded" to various depths. After 22 yr and 14 crops, the productivity of the land from which soil was removed has been improved but not fully restored. Although green manuring with yellow sweet clover improved soil structure, wheat yields were not improved because of competition for soil moisture and poorer in-crop weed control in this part of the rotation. The addition of 45 kg N plus 90 kg P2O5 per hectare in each crop year to sites from which 8–10, 10–20, or 46 + cm of soil had been removed resulted in yield increases of 18, 46, and 70%, respectively, over the unfertilized check of each treatment; the average yields were 104, 91, and 70%, respectively, of the undisturbed, unfertilized (check) treatment. On "erosion" treatments where only 8–10 cm of soil were removed, 45 kg N plus 22 kg P2O5 per hectare were sufficient to restore the productivity. Precipitation apparently had a greater effect than fertilizer application on wheat yields. The loss of organic matter and associated soil structure characteristics seemed to be critical factors contributing to yield losses associated with soil erosion. These results show that it is more practical to use management practices that prevent soil erosion than to adopt the practices required to restore eroded soil. Key words: Soil erosion, topsoil loss, water-stable aggregates, soil organic matter, green manure, precipitation


1975 ◽  
Vol 55 (4) ◽  
pp. 481-490 ◽  
Author(s):  
S. DUBETZ ◽  
G. C. KOZUB ◽  
J. F. DORMAAR

Barnyard manure, N fertilizer, corn stovers, and sugar beet tops were incorporated into the soil singly and in combination in an irrigated four-course rotation (sweet corn, soft spring wheat, sugar beets, and sugar beets) that completed four cycles. The application of manure at 27 t/ha every 4 yr increased the organic matter (OM), N, P, and K of the soil and increased yields of 1st-yr sugar beets by 31% in the last cycle. When 66 kg N/ha was combined with the manure, yields of 1st-yr sugar beets increased by 53%. The responses by the 2nd-yr sugar beets were smaller. Manure, and manure plus N fertilizer, increased yields of sweet corn by 11 and 28%, but wheat yields were unaffected. The benefits of manure and N fertilizer became apparent during the second cycle and increased with advancing years. The effects of the crop residue treatments were less pronounced than those of the fertility treatments and took longer to become manifest. Incorporating sugar beet tops or corn stovers into the soil increased beet and corn yields but not wheat yields. Sugar beet yields responded more to the residue treatments when grown without manure or N fertilizer than when the fertility treatments were included. Soil Ca and Mg were not affected by fertility or residue treatments. The soil amendments affected the chemical characteristics of the OM.


1963 ◽  
Vol 43 (4) ◽  
pp. 441-446 ◽  
Author(s):  
E. H. Hobbs ◽  
K. K. Krogman ◽  
L. G. Sonmor

Eight crops commonly grown in southern Alberta were irrigated when available moisture within the root zone had been depleted to 75, 50, and 25 per cent levels. Over a 3-year period the yields of alfalfa, wheat, barley, sugar beets, corn, peas, and sweet clover reached a maximum at or below the 50 per cent level of minimum available soil moisture. Potatoes produced highest yields at the 75 per cent level. The relationship between availability of water to the crop and the amount of water in the soil was shown to be somewhere between the concepts of constant availability and linear decrease and was not consistent among the various crops.


1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.


Author(s):  
Stefan Krause ◽  
Markus Appel

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.


2005 ◽  
Vol 44 (03) ◽  
pp. 107-117
Author(s):  
R. G. Meyer ◽  
W. Herr ◽  
A. Helisch ◽  
P. Bartenstein ◽  
I. Buchmann

SummaryThe prognosis of patients with acute myeloid leukaemia (AML) has improved considerably by introduction of aggressive consolidation chemotherapy and haematopoietic stem cell transplantation (SCT). Nevertheless, only 20-30% of patients with AML achieve long-term diseasefree survival after SCT. The most common cause of treatment failure is relapse. Additionally, mortality rates are significantly increased by therapy-related causes such as toxicity of chemotherapy and complications of SCT. Including radioimmunotherapies in the treatment of AML and myelodyplastic syndrome (MDS) allows for the achievement of a pronounced antileukaemic effect for the reduction of relapse rates on the one hand. On the other hand, no increase of acute toxicity and later complications should be induced. These effects are important for the primary reduction of tumour cells as well as for the myeloablative conditioning before SCT.This paper provides a systematic and critical review of the currently used radionuclides and immunoconjugates for the treatment of AML and MDS and summarizes the literature on primary tumour cell reductive radioimmunotherapies on the one hand and conditioning radioimmunotherapies before SCT on the other hand.


2017 ◽  
Vol 47 (188) ◽  
pp. 487-494
Author(s):  
Daniel Mullis

In recent years, political and social conditions have changed dramatically. Many analyses help to capture these dynamics. However, they produce political pessimism: on the one hand there is the image of regression and on the other, a direct link is made between socio-economic decline and the rise of the far-right. To counter these aspects, this article argues that current political events are to be understood less as ‘regression’ but rather as a moment of movement and the return of deep political struggles. Referring to Jacques Ranciere’s political thought, the current conditions can be captured as the ‘end of post-democracy’. This approach changes the perspective on current social dynamics in a productive way. It allows for an emphasis on movement and the recognition of the windows of opportunity for emancipatory struggles.


1996 ◽  
pp. 13-23
Author(s):  
Mykhailo Babiy

Political ideological pluralism, religious diversity are characteristic features of modern Ukrainian society. On the one hand, multiculturalism, socio-political, religious differentiation of the latter appear as important characteristics of its democracy, as a practical expression of freedom, on the other - as a factor that led to the deconsocialization of society, gave rise to "nodal points" of tension, confrontational processes, in particular, in political and religious spheres.


2003 ◽  
pp. 15-26
Author(s):  
P. Wynarczyk
Keyword(s):  
The Core ◽  

Two aspects of Schumpeter' legacy are analyzed in the article. On the one hand, he can be viewed as the custodian of the neoclassical harvest supplementing to its stock of inherited knowledge. On the other hand, the innovative character of his works is emphasized that allows to consider him a proponent of hetherodoxy. It is stressed that Schumpeter's revolutionary challenge can lead to radical changes in modern economics.


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