摘要:

The effect of physical treatments such as drying, freezing, and heating on acetylene (C2H2) reduction (nitrogen fixation) in 3 types of soils was measured. Most treatments significantly affected ethylene (C2H4) production in the sandy loam. None of the treatments suppressed C2H4formation in the sandy clay loam before 2 days. Muck soil with treatments of air‐drying, freeze‐drying, and freezing did not show different patterns in C2H4production. However, auto claving and oven‐drying resulted in a pronounced increase in formation of C2H4. With exception of the heat treatments, no significant decreases in numbers of non‐symbiotic nitrogen‐fixers in soils were observed.

ISSN:0010-3624    

DOI:10.1080/00103627709366753

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Uptake of Co by corn (Zea mays) and bush beans (Phaseolus vulgaris) seedlings was affected by plant species, soil type and soil amendment. Bean leaves preferentially accumulated60Co in comparison with corn leaves. Both the DTPA and (lime and DTPA) treatments enhanced60Co uptake by both plant species, notably in the Troup soil which had lower cation exchange capacity (CEC) and lower soil fertility in comparison with Dothan soil. Conversely, soils with lime but without the chelating agent suppressed60Co uptake. This dictates that farming practices should be closely evaluated if crops for livestock and human consumption are to be raised in fields contaminated by radionuclides.

ISSN:0010-3624    

DOI:10.1080/00103627709366754

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The fourth, fully‐expanded leaves at sweet potato vine tips were sampled at harvest from two separate but similar experiments on njala upland soils after 7 years bush fallow to study the effects of timing and rates of K fertilizers on leaf nutrients and their relationships to sweet potato tuber yields. Potash showed significant effects on leaf P, leaf Zn, leaf Ca, leaf Mn, leaf K/P and leaf Ca/Mg. K x timing interaction affected leaf K/Mg and leaf K/P but timing of Z application did affect significantly neither leaf nutrients nor leaf nutrient ratios. Significant quadratic effect of K on tuber yields as well as significant cubic K x timing interaction effect on tuber yields were observed. There were significant negative correlations between tuber yields and leaf N and between tuber yields and leaf P, indicating that increases in either leaf N or leaf P depressed yields. On the basis of coefficient of determination, increases in leaf N contributed significantly more to yield variation than increases in leaf P. Analysis of covariance and multiple regression studies showed lack of significance of 10 nutrients on tuber yields. Sweet potato tissue which reflects differential nutrient levels with significant effect on tuber yields must be sought. Apart from the added fertilizer, the total effect of ether factors which affect nutrient status and crop performance must be considered.

ISSN:0010-3624    

DOI:10.1080/00103627709366755

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Effects of fertilizer timing and placement on the grain yield and leaf nutrients of uninoculated sole‐crop cowpeas in two experiments during the minor cropping season on Njala upland soil of Sierra Leone were studied. Timing and placement and their interaction had no significant effects on grain yield. Placement affected highly significantly lamina Mg, Cu and Co and significantly lamina N and Ca. Placement and timing x placement interaction affected highly significantly petiole N and petiole P respectively. Timing affected highly significantly petiole N, which decreased as fertilizer application was delayed. The spectrum of nutrient distribution in both lamina and petiole was decidedly different. Multiple regression studies indicated that variability in only petiole Mg, Cu and Co significantly contributed to grain yield variability. By the introduction of 15 nutrients (6 lamina and 9 petiole) after examining the linear regression coefficients into a composite multiple regression study, lamina Ca, petiole Fe and petiole Co were selected as significant contributors to grain yield variability with marked improvement in R2. Removal of the effects of the correlated variables produced significances in the effects of fertilizer placement and timing x placement interaction on grain yields.

ISSN:0010-3624    

DOI:10.1080/00103627709366756

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Single buffer‐two pH and two‐buffer adaptations were compared as double buffer features of the SMP method using a group of 54 soils of wide range in lime requirement (LR). Data from both methods were highly correlated both with each other and with Ca(OH)2‐titrated acidity.

ISSN:0010-3624    

DOI:10.1080/00103627709366757

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Lima and snap beans and southern field peas were cultured in a modified Hoagland's solution for 14 days with N supplied as Ca(NO3)2and/or (NH4)2SO4at three N concentrations and five ratios of NO3to NH4. The ratio of NO3/NH4, rather than the N concentrations influenced seedling growth of these vegetable legumes. Maximum seedling growth of lima bean was generally obtained with all combinations of NO3and NH4. A preference for 75% NO3and 25% NH4was observed for snap bean. Southern field pea growth was reduced only when all of the N was supplied as 100% NH4. Ammonium toxicity symptoms, lesions and severe wilting, developed with snap bean and southern field pea within 14 days when cultured with 100% NH4. Lima bean, though reduced in growth, exhibited a tolerance to the 100% NH4treatment.

ISSN:0010-3624    

DOI:10.1080/00103627709366758

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103627709366752

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor