Duration Of Land Use Research Articles

Interactive effects of agricultural management on soil organic carbon accrual: A synthesis of long-term field experiments in Germany

Crop production often leads to soil organic carbon (SOC) losses. However, under good management practice it is possible to maintain and even re-accumulate SOC. We evaluated how different cropland management techniques affected SOC stocks in the topsoil (0–30 cm depth) of 10 long-term experiments (LTE) in Germany. We found that SOC stocks were particularly enhanced by mineral fertilization and organic amendments like straw incorporation and to a smaller degree by irrigation, but only slightly affected by the choice of preceding crops. In agreement with global meta-analyses, liming and reduced tillage had little or even negative effects on SOC storage, but effects also depended on fertilization. Management effects on SOC stocks were dependent on soil texture: sandy soils showed the lowest SOC stocks of 20.9 ± 2.3 (standard error of the mean) Mg ha−1, but exhibited the largest relative response to different management options. Annual changes in SOC stocks ranged from −3.0 ‰ with no mineral N fertilization, to + 6.1 ‰ with farmyard manure application, using the mineral-fertilized and limed treatment as reference. Even higher rates of up to + 10.6 ‰ yr−1 were reached with the combination of irrigation and straw incorporation. Note that the contribution of organic amendments to SOC accrual and thus to climate change mitigation must be adjusted for reduction in SOC at sites from which straw was removed. Overall, the potential of agricultural management to influence and enhance SOC stocks is significant. This potential is controlled by soil type and land-use duration, is largest for sandy soils with overall lowest SOC stocks, and is characterized by antagonistic and synergistic effects of different management practices.

An Anthropocene chronosequence study on upland soils in the northeastern USA

Intensive land use from agricultural activities fundamentally affects the physical structure and nutrient cycling of soils and can lead to increased erosion of sediment that gets stored downslope in legacy deposits. The northeastern USA provides the opportunity to study anthropogenic-induced changes to soils, with a well-documented ~300-year history of land modification. In this study, we investigate impacts on upland soils in northeast Connecticut at two sites used extensively in the 17–20th centuries that are now abandoned and forested along with two modern agriculture sites. We use stone walls present in LiDAR and aerial imagery from 1934 to 2019 to develop an Anthropocene chronosequence with four land use classes (T0, T1, T2, and T3) that vary in terms of duration of land use and time since abandonment. The two abandoned sites differ primarily in terms of average hillslope gradients, and we use transects at the steeper site to investigate the effect of catena position on sediment mobilization and downslope changes. Soil profiles within each class were described and sampled for standard soil analyses and trace metals using pXRF to address the processes of erosion and mixing in the soils. At both sites, A horizon thicknesses increase and B horizon thicknesses decrease with increasing land use duration. The consistent depth to the C horizon across all classes, lack of soil truncations and accumulation of sediment at the base of slopes, and inventories and patterns of Pb in soil profiles all suggest land use impacts led to soil mixing and redistribution along hillslope catenas, but no substantial erosion and soil loss. Therefore, depositional areas such as wetlands, floodplains and millponds in low relief deglaciated landscapes may not contain large quantities of legacy sediment. Furthermore, widely available LiDAR and aerial imagery datasets have the potential to scale up the chronosequence approach and soil impacts described here.

Soil Use Legacy as Driving Factor for Soil Erosion under Conservation Agriculture

Water erosion can cause irreversible depletions in soil quality and crop productivity. The susceptibility of the soil to erosion is affected by current and historical management practices. Historical soil management practices like ploughing or subsoil loosening may lead to irreversible degradations of soils, which in turn increases soil erosion risk. Six “Wischmeier” plots under conservation agriculture, but with different historic treatments regarding soil use and management, were evaluated. These plots were installed in 1984 in Colonia del Sacramento, Uruguay on a Vertic Argiudoll. The objective of this study was to quantify how changes in soil quality, generated by different historical soil use and management over the last 35 years, contribute to current runoff and soil erosion in a cropping system under soil conservation practices using no-till, residue retention and cover crops. Considering differences in soil legacy effects of previous land use, plots were grouped in three treatments with contrasting historic index of agricultural intensification (IAI). The IAI was developed combining the duration of land use under agricultural production and the number and intensity of tillage activity resulting in the treatments: tillage with crop-pasture rotation (TIL_CP), no-tillage under several rotations (NT_Mix) and tillage with continuous cropping (TIL_CROP) with an increasing IAI of 3.5, 7.1 and 11.8, respectively. Rainfall events, runoff water and total, fixed and volatile solids were studied from 2017 to 2019. Soil physical (bulk density, penetration resistance, infiltration rate, aggregate stability), chemical (soil organic carbon (SOC), pH, phosphorous (P-Bray)) and biological properties (particulate organic matter (POM), potentially mineralizable nitrogen (PMN)) were assessed in 2019. Yearly average runoff amounted 209, 579 and 320 mm in 2017, 2018 and 2019, respectively. Yearly average soil losses were 233, 805 and 139 kg/ha with significant differences among years. The lowest soil losses were observed in TIL_CP (231, 615 and 146 kg/ha in 2017, 2018 and 2019, respectively) with lowest IAI of 3.5. Infiltration rate was the lowest in plots with highest IAI. Soil bulk density was highest (1.3 g/cm3) in plots with high IAI. SOC and PMN were lowest in TIL_CROP (3.0% SOC and 34 mg/kg PMN), holding the highest IAI of 11.8. Conservation agriculture minimized soil erosion losses in all plots and years, and erosion was much lower than the maximum tolerable threshold of 7,000 kg/ha for this particular soil. However, in historically intensively tilled and cropped soils, soil quality showed long-term adverse effects pointing towards a reduced resilience of the agricultural system.

Environmental impact of dairy buffalo heifers kept on pasture or in confinement

In western countries buffaloes are emerging as an alternative species for dairy product differentiation. In the near future dairy enterprises will have to meet increasing environmental regulations. Life Cycle Assessment has been widely used to assess the environmental impact of different milk production systems. We aimed to examine the environmental consequences of two dairy buffalo heifer farming systems using the Life Cycle Assessment approach. The primary data were collected from 32 subjects aged 7–8months at the start of the experiment until they reached the age of puberty in about 12months (i.e. at the age of 19–20months). Sixteen animals were group-housed and confined in an indoor slatted floor pen (4m2/animal) with an outdoor paddock (4m2/animal); 16 others free-ranged on a Mediterranean natural pasture. The environmental charges for global warming potential expressed in terms of total emissions of carbon dioxide equivalent (CO2-eq) was 35.7% less in the free-ranging system as compared with the confined system. The main source of pollution for the confined system was biogenic methane (total amount produced=2012kg CO2-eq) followed by CO2 from fossil fuels (total amount produced=1006kg CO2-eq). The environmental charges for acidification potential, eutrophication potential and non-renewable energy use were 86.3%. 60.0% and 81.4% lower in the free-ranging system compared with the confined system, respectively. In the confined system the largest pollutant in terms of acidification potential was ammonia, whereas nitrate leaching in water (total amount produced=3311g SO2-eq) and the use of crude oil (total amount consumed=5684MJ-eq) were the most relevant for eutrophication potential and non-renewable energy use, respectively.Our results represent the first example of study comparing the environmental impact of an intensive dairy farming system with an alternative natural pasture based system in the Mediterranean region and suggest that the conduction of the unproductive part of the cycle on natural pasture can promote the reduction of several sources of pollution both in atmosphere and in water. Conversely, land occupation was higher in the free-ranging system as compared with the confined system (20,349 vs 1381m2year, respectively). However, the software and the database used for this calculation only considered duration of land use and yield per area unit, whereas no relevance was given to the quality of land use in terms of animal welfare promotion, contribution to biodiversity conservation, and maintenance of economically active social communities. Therefore, we suggest that the estimation of the impact categories related to land occupation would include aspects concerning the nature of the land.

Accumulation, sources and health risks of trace metals in elevated geochemical background soils used for greenhouse vegetable production in southwestern China

Greenhouse vegetable cultivation with substantive manure and fertilizer input on soils with an elevated geochemical background can accumulate trace metals in soils and plants leading to human health risks. Studies on trace metal accumulation over a land use shift duration in an elevated geochemical background scenario are lacking. Accumulation characteristics of seven trace metals in greenhouse soil and edible plants were evaluated along with an assessment of the health risk to the consumers. A total of 118 greenhouse surface soils (0–20cm) and 30 vegetables were collected from Kunming City, Yunnan Province, southwestern China, and analyzed for total Cd, Pb, Cu, Zn, As, Hg, and Cr content by ICP-MS and AFS. The trace metals were ordered Cu>Cd>Hg>Zn>Pb>As>Cr in greenhouse soils accumulation level, and the geo-accumulation index suggested the soil more severely polluted with Cd, Cu, Hg and Zn. The greenhouse and open-field soils had significant difference in Cd, Cr and Zn. The duration of shift from paddy to greenhouse land-use significantly influenced trace metal accumulation with a dramatic change during five to ten year greenhouse land-use, and continuous increase of Cd and Hg. A spatial pattern from north to south for Cd and Hg and a zonal pattern for Cu and Zn were found. An anthropogenic source primarily caused trace metal accumulation, where the principal component analysis/multiple linear regression indicated a contribution 61.2%. While the assessment showed no potential risk for children and adults, the hazard health risks index was greater than one for adolescents. The extended duration of land use as greenhouses caused the trace metal accumulation, rotation in land use should be promoted to reduce the health risks.

Impact of Shifting Cultivation on Dense Tropical Woodlands in Southeast Angola

Dry tropical woodlands are the characteristic natural vegetation type of southeast Angola, where precipitation is seasonal and nutrient content of soils is very low. Subsistence farmers overcome the poor abiotic conditions by using shifting cultivation based on specific site selection. We describe the vegetation composition of a previously unstudied dense woodland tract, which is preferred for agriculture, comparing it to nearby open woodland. We placed 25 vegetation plots randomly in the two types of natural woodland vegetation (open and dense) as well as in fallows with three different durations of land use. In each plot the cover of all vascular plant species was recorded. Variables describing vegetation structure, including basal area and leaf area index, were recorded. We analyzed soil samples for texture, pH, conductivity and nutrients, and investigated the impact of land use duration on woodland regeneration. We found that species composition and vegetation structure of the dense woodland differed greatly from the surrounding open woodland. The dense woodland is preferable for agriculture because of its higher soil content of silt, clay and potassium, higher woody biomass, and more abundant soft litter. A longer duration of land use affects species composition and diversity of the regenerating vegetation as well as nutrient content in the soil. In the near future, the increasing demand for agricultural land is likely to change the structure and composition of the dense woodland.

Soil attributes and plant production changes in a tropical littoral wetland

AbstractLake Naivasha is a freshwater lake in the East African Rift Valley. With continued lake level declines between 1980 and 2011, the newly exposed land areas were gradually taken for agricultural use. The resulting chronosequences allow for an analysis of the effects of land use duration on nutrient dynamics and agricultural production. Transects representing land use durations of 0–30 (cropland) and 15–30 years (pasture) were established on soils formed on alluvial deposits and lacustrine sediments. We assessed changes in topsoil nitrogen (N) stocks (t ha−1), ammonium mineralization potential (N‐supplying capacity), and plant‐available P with increasing durations of land use. An additional greenhouse experiment studied the responses of kikuyu grass (Cenchrus clandestinus) and maize (Zea mays) in potted topsoil collected from differnt land‐use types and chronosequence positions. With increasing duration of land use we noted a significant decline (P < 5%) in soil N contents under both pasture and cropland uses, following a model of exponential decay. The N stocks decreased at 84 kg ha−1 a−1 and a decay rate constant of 0.019 a−1 in pasture soil within 15 years, and at 75 kg ha−1 a−1 with a decay rate‐constant of 0.013 a−1 in cropland soil within 30 years. While the ammonium‐N mineralization potential also decreased with land use duration, the trends were significant only in lacustrine pasture soils. Plant‐available P did not show any trends that were related to the duration of land use. Kikuyu grass and maize accumulated less dry matter and N as the duration of use increased. This biomass accumulation was significantly related to soil N. A continued mineralization of soil organic matter has possibly contributed to the observed soil N depletion over time. The continuous agricultural use of the littoral wetland zone of Lake Naivasha is likely to entail declining production potentials for both pastures and food crops.

English

  The study was conducted to examine the effects of property rights and other factors on the outputs of maize, yam and cassava in three zones of Osun State in Nigeria. This study employed a multi-stage sampling technique to select 105 farmers involving growers of maize, yam and cassava in the study area. Data were analyzed with the aid of descriptive statistics, budgetary techniques and a multiple linear regression model. The results of budgetary analysis showed that variable cost was highest in yam production. The average revenues per hectare for maize, yam and cassava were (N is Nigerian currency equivalent to about $0.0067) N104, 487.50, N583, 846.20 and N438, 208.50, respectively. However, the average net incomes were N19, 908.40, N432, 079.00 and N96, 543.90 for maize, yam and cassava, respectively. Based on the rates of returns, N1 invested in each of maize, yam and cassava production yielded N1.2, N3.4 and N3.1, respectively implying that yam was the most profitable crop in the study area. The result of the multiple regression model revealed that farm size significantly affect the outputs of the three crops. Land rights type (having either use right/use and transfer right) and security of land defined by duration of land use affected maize output while duration and ownership type affected yam output, whereas, duration only affect cassava output. There is therefore the need to review the land distribution and administration policies based on the identified significant factors affecting each crops.   Key words: Nigeria, Osun State, crops, maize, yam, cassava, land rights.

A meta-analytical global comparison of aboveground biomass accumulation between tropical secondary forests and monoculture plantations

Secondary forests and monoculture plantations are widespread in the tropics and are the two most common forms of reforestation. To assess the value of both systems for CO2 mitigation, we performed a systematic analysis of the two systems comparing growth rates and potential to store carbon. The increasing involvement of these forest types in carbon trading makes a pertinent issue. We used a meta-analytical approach to evaluate relative rates of aboveground growth (biomass accumulation) in secondary forests and monoculture plantations, controlling for climate and site characteristics. We find a general tendency for aboveground biomass accumulation (ABA) to be marginally higher in plantations than secondary forests. Three recorded site factors were significantly associated with ABA, but differed between reforestation types. Plantation growth rates were negatively correlated with precipitation seasonality, while growth rates of secondary forest were positively correlated with surrounding tree cover and negatively correlated with duration of prior land use. It is noteworthy that poor reporting of site history such as prior land-use duration, particularly in monoculture plantations, and a strong bias in studies towards measuring young forest plots obfuscates evaluation of some ecological drivers and long-term processes. We conclude that the difference in ABA between tropical secondary forests and monoculture plantations is smaller than previously assumed, emphasising the potential of secondary forests for low-cost carbon storage and biomass production, particularly in landscapes with high existing tree cover or highly seasonal rainfall.

Accumulation of Miscanthus‐derived carbon in soils in relation to soil depth and duration of land use under commercial farming conditions

AbstractBioenergy is becoming an important option in Global Change mitigation policy world‐wide. In agriculture, cultivation of energy crops for biodiesel, biogas, or bioethanol production received considerable attention in the past decades. Beyond this, the cultivation of Miscanthus, used as solid fuel for combustion, may lead to an increase in soil organic matter content compared to other agricultural land use, since C‐sequestration potential in soils of Miscanthus crops is high due to, e.g., high amounts of harvest residues. This may indirectly contribute to a reduction of atmospheric CO2 concentration. The objective of the present work was to investigate the development of soil organic carbon and Miscanthus‐derived C contents, as well as to estimate carbon stocks in soils cultivated with Miscanthus using 13C‐natural‐abundance technique. The investigations were carried out in relation to soil depth up to 150 cm in a sequence of 2, 5, and 16 y of cultivation relative to a reference soil cultivated with cereals. Amounts of total organic C (TOC) and Miscanthus‐derived C (Miscanthus‐C) increased with increasing duration of cultivation. For example, TOC increased from 12.8 to 21.3 g C kg–1 after 16 y of cultivation at the depth of 0–15 cm, whereby the portion of Miscanthus‐C reached 5.8 g C kg–1. Also within deeper soil layers down to 60 cm depth a significant enhancement of Miscanthus‐C was detectable even though TOC contents were not significantly enhanced. At soil depth below 60 cm, no significant differences between treatments were found for Miscanthus‐C. Within 16 y of continuous commercial farming, Miscanthus stands accumulated a total of 17.7 Mg C ha–1 derived from Miscanthus residues (C4‐C), which is equivalent to 1.1 Mg C4‐C ha–1 y–1. The annual surplus might function as CO2 credit within a greenhouse‐gas balance. Moreover, the beneficial properties of Miscanthus cultivation combined with a low requirement on fertilization may justify the status of Miscanthus as a sustainable low‐input bioenergy crop.

Establishing a minimum dataset for soil quality assessment based on soil properties and land-use changes

To assess soil quality, a minimum dataset (MDS) of soil properties has to be proposed commonly through calculating the total load of each candidate soil parameter on all of the qualified principal components by use of principal component analysis (PCA) and Norm-value computation. Considering intensive land-use changes, the method introduced in this study on MDS establishment integrates the quantified contributions of land-use type and land-use duration on each soil parameter by using multivariate analysis and mean multiple comparison. In this way, a MDS maximally representing all candidates with minimal loss of the soil quality information contained by those non-MDS soil parameters is established. The MDS proposed can not only well integrate the quantified influence of land-use changes and land-use duration on soil parameters, but is also quite flexible and extendable with the potential to be extrapolated to assess soil quality in other regions. Based on two sets of soil database obtained separately in 1985 and 2004, two MDSs established are compared with each other. It is found that only quite a small change in MDS components occurs during a 20-year period. For a better assessment of soil quality, it seems necessary to examine on what kind of temporal scale and how much MDS will change for a site-specific area with intensive land-use changes.