Heavy rainfall in peak growing season had larger effects on soil nitrogen flux and pool than in the late season in a semiarid grassland

2022 ◽  
Vol 326 ◽  
pp. 107785
Author(s):  
Linfeng Li ◽  
Yanbin Hao ◽  
Zhenzhen Zheng ◽  
Weijin Wang ◽  
Joel A. Biederman ◽  
...  
1971 ◽  
Vol 49 (10) ◽  
pp. 1821-1832 ◽  
Author(s):  
Edward Sucoff

During the 1969 and 1970 growing season buds were collected almost weekly from matched trees in northeastern Minnesota. Cataphyll primordia for the year n + 1 shoot began forming at the time that internodes in the year n shoot started elongating (late April) and continued forming until early September. Primordia for axillary buds started forming about 2 months later and stopped forming at the same time as cataphylls. The size and deposition activity of the apical dome simultaneously increased during the early growing season and decreased during the late season. The maximum rates in July were over nine cataphylls per day.Rate of cataphyll deposition paralleled elongation of the needles on subtending shoots. Forty to fifty percent of the cataphylls had been formed when shoot growth was 95% complete. Although the bulk of the depositions occurred earlier in 1970, when growing degree days were used as the clock, the 2 years were similar.The results provide quantitative data to complement the histologic emphasis of previous studies.


1995 ◽  
Vol 46 (7) ◽  
pp. 1401 ◽  
Author(s):  
RR Gault ◽  
MB Peoples ◽  
GL Turner ◽  
DM Lilley ◽  
J Brockwell ◽  
...  

Nodulation, N2 fixation (estimated by 15N natural abundance methods) and dry matter production were studied in a lucerne (Medicago sativa) crop managed for hay production at Ginninderra Experiment Station, A.C .T. Measurements were taken in the year of establishment and during two subsequent growing seasons. There were three treatments: (1) no inoculation and no annual fertilizer applied, (2) initial inoculation and superphosphate applied annually, (3) no inoculation, superphosphate applied annually and ammonium sulfate periodically. Before planting and after each growth season, soil was analysed for extractable mineral nitrogen, total nitrogen and the 15N natural abundance of this nitrogen, to the depth explored by lucerne roots. Before planting, no appropriate root-nodule bacteria (Rhizobium meliloti) were detected in the soil and initially plants were nodulated only in the inoculated treatment. Thereafter nodulation increased on the other treatments. Eight months after sowing there were no differences between treatments in numbers of R. meliloti g-l soil or in nodulation. In the third growing season, almost 30 kg ha-1 (dry wt) of nodules were recovered to a depth of 25 cm. These nodules were primarily located on fine, ephemeral roots and many appeared to be renewed after cutting of the lucerne. In the year of establishment, dry matter yields (0% moisture) totalled 3 to 4 t ha-1 in three hay cuts. In succeeding years, total yields were in the range 10 to 13 t ha-1 in four or five cuts per season. Nitrogen removed in the harvested lucerne reached 340 to 410 kg N ha-lyr-l in the second and third years and between 65 and 96% of this N arose from N2 fixation, depending on the method of calculation used. Poorer dry matter production and N2 fixation in treatment 1 in the third growing season was attributed to an insufficient supply of available phosphorus. Fixed N removed in Lucerne hay from treatment 2 totalled at least 640 kg N ha-1 in the three years of the experiment. Also, there were substantial increases in soil nitrogen due to lucerne growth. Although soil compaction made the quantification difficult, at the end of the experiment it was estimated that there was at least an extra 800 kg N ha-1 in the total soil nitrogen under lucerne compared to strips of Phalaris aquatica grown between the lucerne plots. It was concluded that lucerne contributed at least the same amount of fixed nitrogen to the soil as was being removed in the harvested hay.


2010 ◽  
Vol 45 (3) ◽  
pp. 187-192 ◽  
Author(s):  
Hongtao Zhao ◽  
Xuelin Zhang ◽  
Sutie Xu ◽  
Xiaoguang Zhao ◽  
Zhongbing Xie ◽  
...  

HortScience ◽  
1996 ◽  
Vol 31 (5) ◽  
pp. 798-801 ◽  
Author(s):  
Unaroj Boonprakob ◽  
David H. Byrne ◽  
Dale M.J. Mueller

Actively growing shoots of peach [Prunus persica (L.) Batsch] were collected every 2 weeks throughout the 1989 growing season. The samples were sectioned longitudinally and transversely to observe axillary bud initiation, which occurred in all samples collected. Differentiation of axillary bud meristems from early season samples (mostly normal nodes) included apical and prophyll formation, with procambium connected to the stem procambium. Little to no differentiation of such structures occurred in the late-season samples (mostly blind nodes). Other results suggest that blind node formation is a consequence of a lack of bud differentiation rather than a failure of bud initiation.


Author(s):  
L.P. Chapman

From the farming point of view the high country of the South Island of New Zealand is generally taken to mean all the high native grassland devoted to the growing of wool and store stock and subject to risk of Slidui. This covers some 12 million acres of country with a great variety of topography, climate, and soils, Rainfalls range from 1%. in the arid regions of Otago to over 100in. in the heavy rainfall areas close to the main ranges, and soils and vegetation vary accordingly. The winter is long and the growing season short, a maximum of 6 months in most districts.


1992 ◽  
Vol 72 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G. P. Lafond

A study was conducted to evaluate European cereal management techniques in winter wheat under semi-arid growing conditions. Combinations of rates and split applications of ammonium nitrate fertilizer with a plant growth regulator and/or a late season fungicide application were investigated using no-till "stubbled-in" production practices in two winter wheat cultivars, Norwin and Norstar at two locations over 3 yr. Nitrogen fertilizer gave the maximum yield when it was applied in mid-April. Split applications of nitrogen did not improve grain yields or grain protein concentration. A height reduction was observed with the use of plant growth regulators in both cultivars but no benefits were incurred due to the lack of lodging. The late season fungicide application had some effect on increasing kernel weight in both cultivars but rarely translated into a higher yield. Nitrogen and growing conditions had the largest effects on yield and the dilemma faced by producers is to correctly match nitrogen rates with environmental conditions given that the nitrogen has to be applied early in the spring. Available spring soil moisture and soil residual nitrogen provided little help in determining the rate of nitrogen giving the maximum economic yield because assumptions on growing season precipitation have to be made. It is suggested that nitrogen management be based on a risk analysis which would involve determining the probability of different levels of growing season precipitation for various climatic zones and soil types and the corresponding yield levels expected. Rates of nitrogen fertilizer would then be adjusted according to soil residual nitrogen levels and the risk the producer is willing to assume. This will require more extensive research and development of crop production models.Key words: Nitrogen fertilizer, Triticum aestivum L., intensive cereal management, propiconazole, chlormequat chloride, ethephon


2017 ◽  
Vol 24 (3) ◽  
pp. 1001-1011 ◽  
Author(s):  
Jingyi Ru ◽  
Yaqiong Zhou ◽  
Dafeng Hui ◽  
Mengmei Zheng ◽  
Shiqiang Wan

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