The effects of soil texture and soil moisture on photosynthesis, growth and nitrogen uptake of scotch pine seedlings

Hydrological models require the determination of fitting parameters that are tedious and time consuming to acquire. A rapid alternative method of estimating the fitting parameters is to use pedotransfer functions. This paper proposes a reliable method to estimate soil moisture at -33 and -1500 kPa from soil texture and bulk density. This method reduces the saturated moisture content by multiplying it with two non-linear functions depending on sand and clay contents. The novel pedotransfer function has no restrictions on the range of the texture predictors and gives reasonable predictions for soils with bulk density that varies from 0.25 to 2.16 g cm-3. These pedotransfer functions require only five parameters for each pressure head. It is generally accepted that the introduction of organic matter as a predictor improves the outcomes; however it was found by using a porosity based pedotransfer model, using organic matter as a predictor only modestly improves the accuracy. The model was developed employing 18 559 samples from the IGBP-DIS soil data set for pedotransfer function development (Data and Information System of the International Geosphere Biosphere Programme) database that embodies all major soils across the United States of America. The function is reliable and performs well for a wide range of soils occurring in very dry to very wet climates. Climatical grouping of the IGBP-DIS soils was proposed (aquic, tropical, cryic, aridic), but the results show that only tropical soils require specific grouping. Among many other different non-climatical soil groups tested, only humic and vitric soils were found to require specific grouping. The reliability of the pedotransfer function was further demonstrated with an independent database from Northern Italy having heterogeneous soils, and was found to be comparable or better than the accuracy of other pedotransfer functions found in the literature. Key words: Pedotransfer functions, soil moisture, soil texture, bulk density, organic matter, grouping

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A computational history and outlook of nitrogen use efficiency and precipitation-optimal fertilisation timings in agriculture

10.5194/ismc2021-11 ◽

2021 ◽

Author(s):

Daniel McKay Flecher ◽

Siul Ruiz ◽

Tiago Dias ◽

Katherine Williams ◽

Chiara Petroselli ◽

...

Keyword(s):

Soil Moisture ◽

Nitrogen Uptake ◽

Nitrogen Use Efficiency ◽

Nitrogen Efficiency ◽

Nitrogen Use ◽

Plant Nitrogen ◽

Nitrogen Fertilisation ◽

Plant Nitrogen Uptake ◽

Use Efficiency ◽

Rainfall Patterns

Half of the nitrogen applied to arable-fields is lost through several processes linked to soil moisture. Low soil moisture limits nitrogen mobility reducing nitrogen-uptake while wetter conditions can increase nitrogen leaching. Rainfall ultimately governs soil moisture and the fate of nitrogen in soil. However, the interaction between rainfall and nitrogen use efficiency (NUE) remains poorly understood. We developed a field-scale modelling platform that describes coupled water and nitrogen transport, root growth and uptake, rainfall, the nitrogen-cycle and leaching to assess the NUE of split fertilisations with realistic rainfall patterns. The model was solved for every possible split fertilisation timing in 200+ growing seasons to determine optimal timings. Two previous field trials regarding rainfall and NUE had contrasting results: wetter years have enhanced fertiliser loss and drier years reduced plant nitrogen uptake. By choosing appropriate fertilisation timings in the model we could recreate the two contrasting trends and maintain variability in the data. However, we found by choosing other fertilisation timings we could mitigate the leaching in wetter years. Optimised timings could increase plant nitrogen uptake by up to 35% compared to the mean in dry years. Plant uptake was greatest under drier conditions due to mitigated leaching, but less likely to occur due to low nitrogen mobility. Optimal fertilisation timings varied dramatically depending on the rainfall patterns. Historic and projected rainfall patterns from 1950-2069 were used in the model. We found optimal NUE has a decrease from 2022-2040 due to increased heavy rainfall events and optimal fertilisation timings are later in the season but varied largely on a season-to-season basis. The results are a step towards achieving improved nitrogen efficiency in agriculture by using the &#8216;at the right time&#8217; agronomic-strategy in the &#8216;4Rs&#8217; of improved nitrogen fertilisation. Our results can help determine nitrogen fertilisation timings in changing climates.

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Effect of Bearmat (Chamaebatia foliolosa) on Soil Moisture and Ponderosa Pine (Pinus ponderosa) Growth

Weed Science ◽

10.1017/s0043174500026254 ◽

1982 ◽

Vol 30 (1) ◽

pp. 98-101 ◽

Cited By ~ 5

Author(s):

John C. Tappeiner ◽

Steven R. Radosevich

Keyword(s):

Acetic Acid ◽

Soil Moisture ◽

Pinus Ponderosa ◽

Ponderosa Pine ◽

Tree Height ◽

Wood Production ◽

Pine Seedlings ◽

Survival And Growth ◽

Dichlorophenoxy Acetic Acid

An experiment was established in 1961 to determine the influence of bearmat (Chamaebatia foliolosa Benth.) competition on ponderosa pine (Pinus ponderosa Laws.) survival and growth. Ponderosa pine seedlings were planted in bearmat which was: (A) untreated, (B) sprayed with a mixture of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], and (C) eliminated by a combination of herbicide, clipping sprouts, and trenching to prevent root and rhizome invasion. Ponderosa pine survival after 19 yr averaged 9%, 66%, and 90%, respectively, for the three treatments. Tree height after 19 yr averaged 1.6, 1.9, and 5.7 m for treatments A, B, and C, respectively. Soil moisture use was initially less on the herbicide-treated than on the untreated plots, but bearmat quickly sprouted after application to compete with the pine seedlings for moisture. After 19 yr the bearmat was more dense and appeared to be more vigorous on the sprayed plots than on those receiving no treatment. We estimate that 75% reduction in net wood production could result after 50 yr on this site from bearmat competition.

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TIME OF SAMPLING AFTER AN IRRIGATION TO DETERMINE FIELD CAPACITY OF SOIL

Canadian Journal of Soil Science ◽

10.4141/cjss65-024 ◽

1965 ◽

Vol 45 (2) ◽

pp. 171-176 ◽

Cited By ~ 7

Author(s):

J. C. Wilcox

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Texture ◽

Soil Moisture Content ◽

Field Capacity ◽

Percentage Error ◽

High Positive Correlation ◽

Positive Correlation

Drainage curves following irrigation were determined at six depths in eight soils having unrestricted drainage but varying widely in soil texture. The field capacities were determined under relatively high rates of evapotranspiration. The time after irrigation that it was necessary to wait before sampling the soil, to determine field capacity, was also determined. A high positive correlation was obtained between the log of field capacity in inches and the log of time after irrigation at which to sample the soil. The time varied from about 0.5 day with 1.5 in. field capacity to 4.0 days with 35 in. From the curves of soil moisture content versus time, the errors caused by sampling too soon or too late were determined. The percentage error (i.e. percent of field capacity) increased with an increase in the error in time of sampling; it decreased with an increase in field capacity in inches; and it was greater when sampling was too soon than when it was too late.

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