Pii: S1161-0301(00)00068-x
نویسندگان
چکیده
The release of nitrogen by roots of intact spring wheat plants into the soil and other losses, mainly of volatile N, have been investigated in two subsequent years from tillering until maturation, by use of a new technique for plant labelling with N. Plants were at first labelled by growing them in a N nutrient solution until tillering and then after thoroughly washing the roots with distilled water, the entire plants were transplanted into pots filled with a silty loam. N release was analysed throughout the growth of the plants at 6 days after transplantation (tillering), ear emergence, beginning of grain filling, and full maturation. At these stages N was analysed in the plant and in the soil. Release rates of labelled N into the soil were low in the period from tillering to ear emergence and increased progressively attaining maximum rates in the phase from ear emergence to grain filling. The non-accounted for losses of labelled N, mainly volatile losses, were also found to be highest from ear emergence to the beginning of grain filling. © 2000 Elsevier Science B.V. All rights reserved.
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Pii: S1161-0301(00)00074-5
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Pii: S1161-0301(00)00079-4
A precise prediction of the yield losses inflicted by weeds is the basis of decisions in weed management. Hitherto, only rough estimates, which neglect the specific production situation, have been available for vegetable crops. In this study a simple simulation model was developed to estimate yield loss by radiation competition as a function of environmental variables. In the model, the distrib...
متن کاملPii: S1161-0301(00)00061-7
Use of precision farming technologies requires better understanding of soil variability in physical, hydraulic and chemical properties. Some of that variation is natural, some is the result of the management history of the field. So, to match agricultural inputs and practices to site-specific conditions, the factorial kriging algorithm (FKA) was used to analyze spatial variability in some soil ...
متن کاملPii: S1161-0301(00)00087-3
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