Growth and nitrogen uptake of jack pine seedlings in response to exponential fertilization and weed control in reclaimed soil

We evaluated the impact of exponential fertilization in nursery and weed removal in the field on growth and nitrogen (N) retranslocation and uptake from the soil of jack pine (Pinus banksiana Lamb.) seedlings planted on an oil sands reclaimed soil. Exponential fertilization is a method of supplying nutrients at an exponential rate to achieve constant internal nutrient concentrations in seedlings without changing their size during their growth in the nursery. The N retranslocation in seedlings was traced using ¹⁵N isotope labeling. Exponential fertilization increased nutrient reserve in the seedling in nursery production, and increased height (P = 0.003), root collar diameter (P < 0.001), total biomass (P < 0.001), and N content (P < 0.001) of seedlings at the end of first growing season in the field growth. Conventionally fertilized seedlings allocated a greater percent of biomass to roots than to current-year needles. The ¹⁵N isotope analysis showed that 59 to 82% of total N demand of new growth was met by retranslocation from old tissues. Exponential fertilization increased N retranslocation by 147% (P < 0.001) and N uptake from the soil by 175% (P = 0.012). Weed removal marginally increased (P = 0.077) N uptake from the soil but decreased (P = 0.046) N retranslocation with no net effect on total N content in new tissues. We conclude that exponential fertilization improves the early growth of jack pine and can help improve revegetation in reclaiming disturbed oil sands sites.     

Potential use of δ13C, δ15N, N concentration, and Ca/Al of Pinus densiflora tree rings in estimating historical precipitation pH

Purpose  

The chemistry of annual tree growth rings is affected by precipitation pH, and tree rings store information on environmental conditions at the time of ring formation. The purpose of this study was to evaluate the potential use of tree ring chemistry data in estimating historical precipitation pH using the relationship between precipitation pH and tree ring chemistry.     

Land use types with different fertilization management affected isotope ratios of bulk and water-extractable C and N of soils in an intensive agricultural area

Journal of Soils and Sediments - This study was conducted to investigate variations in the stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) of agricultural soils under different...     

Relating Tree Ring Chemistry of Pinus densiflora to Precipitation Acidity in an Industrial Area of South Korea

To test the possible use of tree ring chemical properties as proxies for precipitation acidity ([H⁺]), we investigated the relationships between tree ring chemistry (δ¹³C, δ¹⁵N, Ca-to-Al ratio, and N concentration) of Pinus densiflora and precipitation [H⁺] between 1992 and 2005 in an industrial area in the southwest region of South Korea. Statistical analyses showed that all tree ring chemistry parameters were significantly correlated with precipitation [H⁺]. Tree ring δ¹³C was negatively correlated with precipitation acidity (r?=??0.67, P?<?0.01), reflecting the photosynthetic fixation of ¹³C-depleted CO₂ from fossil fuel combustion that would be the primary source of precipitation acidity. A positive correlation of N concentration (r?=?0.89, P?<?0.001) and a negative correlation of δ¹⁵N (r?=??0.63, P?<?0.05) in tree rings with precipitation acidity most likely reflected the influence of ¹⁵N-depleted N compounds deposited via precipitation. The Ca-to-Al ratio was negatively (r?=??0.58, P?<?0.05) correlated with precipitation acidity, indicating that soil acidification caused the loss of Ca from the soil and solubilization of Al resulting from acid precipitation. Such relationships suggest that δ¹³C, δ¹⁵N, N concentration, and Ca-to-Al ratio in tree rings can be reliably used to evaluate the impact of acid precipitation on the studied P. densiflora stands.     

Warming Increased Nitrogen Availability and Tree Growth During the Last Five Decades as Revealed by Annual Ring Data of Pinus merkusii in Central Vietnam

The effects of climate change including warming on nitrogen (N) availability and growth of Pinus merkusii in central Vietnam were investigated using the relationship between climate variables (rainfall and temperature) and tree-ring parameters (ring width, density, basal area increment, and N concentration) for the last five decades. Rainfall was not correlated with any tree-ring parameters, indicating that water availability did not limit tree growth in the study site probably due to sufficient rainfall. Temperature was positively correlated with ring N concentration, basal area increment, and ring density, probably reflecting the positive effects of warming on soil N mineralization, net photosynthesis, and cell wall thickness, respectively. Therefore, this study suggested that global warming during the last five decades increased N availability and the increased N further helped warming-induced increases in the growth of P. merkusii in central Vietnam.     

Sorption of Pb in chemical and particle-size fractions of soils with different physico-chemical properties

Journal of Soils and Sediments - Lead (Pb) sorption capacity (PbSmax) and distribution in chemical and particle-size fractions of six soils with different physico-chemical properties were...     

Fly ash and zeolite amendments increase soil nutrient retention but decrease paddy rice growth in a low fertility soil

Purpose

Fly ash (FA) and zeolite (Z) are known to increase nutrient retention in paddy soils through the immobilization of phosphorus (P) by FA and nitrogen (N) by Z. However, there is a possibility that the co-application of the amendments may hamper rice growth due to reduced availability of the nutrients. This study was conducted to investigate the effects of the co-application of FA and Z on soil N and P availability and rice growth.

Materials and methods

Rice was cultivated in soils without the amendment (control) and with the amendment: FA alone, Z alone, and both FA and Z. Tiller number, dry matter (DM), rice uptake of N and P, and soil N and P concentrations were determined.

Results and discussion

The application of FA and Z increased N and P concentrations in the soils; however, such increased nutrient retention did not translate to DM increases. Results suggested that reduced mobility of nutrients hampered tillering in the early growth period, eventually leading to a reduction in DM accumulation at the harvest. Due to the nutrient limitation caused by FA and Z, the rice grown with both FA and Z did not survive at the harvest.

Conclusions

Our study shows that the application of FA and Z does not always improve rice growth due to nutrient limitation, especially in a low fertility soil. Furthermore, the co-application of FA and Z should be avoided, as the negative impact of FA or Z on nutrient limitation became more severe when FA and Z were co-amended.

     

Compost type effects on nitrogen leaching from Inceptisol,Ultisol, and Andisol in a column experiment

Purpose  

To more efficiently utilize composts as N sources while minimizing the environmental impact, it is necessary to understand the effects of compost type on N mobility in compost-amended soil with different characteristics. The objectives of this study are to investigate the effects of livestock manure composts on N leaching from soils and to identify the principal physicochemical variables of the composts that affect N leaching.     

Reclamation of desert land to continuous cotton cropping affects soil properties and microbial communities in the desert-oasis ecotone of Xinjiang,China

Purpose

A large area of desert land in the desert-oasis ecotone in northwestern China is being reclaimed for continuous cotton production for several decades. However, little is known about the possible effect of reclamation and long-term monocultural cotton cultivation on soil properties and microbial communities in the desert-oasis ecotone area.

Materials and methods

Soil samples were collected from the 0–20-cm mineral soil from croplands that had been continuously planted cotton for 5, 25, and 50 years after reclamation, as well as a desert land (t?=?0, before reclamation, used as the control). Soil physical and chemical properties, enzyme activities, and bacterial and fungal community diversities were determined.

Results and discussion

Soil organic carbon, total nitrogen, and enzyme activities increased up to 25 years after reclamation, and further monocultural cotton cropping was not beneficial to improve soil quality. Soil urease, alkaline phosphatase, and sucrase activities increased by 121~205%, 100~167%, and 206~719% in croplands as compared with the desert land, respectively, after reclamation with the highest value at 25 years of cotton cultivation. Bacterial richness and diversity increased from desert land to the 5-year-old cropland and then remained stable after 5 years of cotton cropping, and soil fungal richness and diversity were not affected by reclamation and cropping years.

Conclusions

Crop rotation or fallow should be considered to maintain or improve soil quality over the long-term monocultural cropping.