Decreased Soil Bulk Density Research Articles

EFFECT OF LAND PREPARATION, WATER MANAGEMENT PRACTICES, AND PLANTING OPERATION ON PLANTING QUALITY IN RICE PRODUCTION

This study was conducted at Sungai Burong Tanjung Karang Kuala Selangor, Malaysia to investigate the effects of planting methods and techniques on planting quality. The problem is that the farmers do not follow Rice Check quality points in land preparations for flooding, drainage, and water depth which affects the planting quality (planting density, spacing, and planting losses). The results showed that following standardized practices has a positive effect on planting quality. Soil penetration resistance and soil bulk density decrease with the increase of the field flooding period and increase with the sedimentation period increase. Soil penetration resistance and bulk density have a negative effect on planting losses. The working speed of the transplanting machine was affected by the field condition SPR, Db, and WC affect the transplanting speed which affects the planting quality (planting density, spacing, and planting losses). The flooding period has a positive effect on planting losses, while the sedimentation period has a negative effect. Floating hills and buried hills decrease with the increase of flooding periods, and water depth, and with the decrease of the sedimentation soil penetration resistance, and soil bulk density. Bulk density and soil penetration resistance have a positive effect on planting density and spacing as they decrease, planting density and spacing decreases, and vice versa. The flooding period has a negative effect on planting density and spacing, while the sedimentation period has a positive effect. About 50.5% of the farmers used the right required amount of water for irrigation, and also the right time for irrigation.

Effects of Biochar, Lime, and Compost Applications on Soil Physicochemical Properties and Yield of Pomelo (Citrus grandis Osbeck) in Alluvial Soil of the Mekong Delta

Soil acidity is an important factor affecting crop productivity in the tropics. The soil of the Vietnamese Mekong Delta has high acidity, deficient levels of exchangeable bases, and low fertility. This study aimed to evaluate soil amendments’ role in improving soil fertility, soil acidity, and pomelo yield cultivated in raised beds. The field trial was carried out in Hau Giang Province consecutively over 3 years from 2018 to 2020. Four treatments were used, namely control, biochar (5 ton·ha−1·year−1), lime (2 ton·ha−1·year−1), and compost (5 ton·ha−1·year−1). All treatments applied the same amount of NPK fertilizers at rates of 400 kg·N, 300 kg·P2O5, and 400 kg·K2O·ha−1·year−1. Physicochemical properties of the topsoil (0–20 cm) and subsoil (20–40 cm) and fruit yield were investigated. The results showed that biochar or compost application increased soil pH, soil organic matter (SOM), and exchangeable cations and decreased soil bulk density (BD), improving soil fertility and fruit yield in the raised beds. Applications of biochar or compost resulted in about 1.5-fold higher fruit yield than that of chemical fertilizer alone. The average profit increased to USD 1,672 ha−1 after applying biochar and compost in the three-year experiments. Biochar and compost amendments have a positive effect on reducing soil acidity and soil BD, elevating SOM, supplying available Ca2+ and Mg2+, improving soil fertility, enhancing fruit yield, and increasing profit.

Effects of organic amendments and ridge–furrow mulching system on soil properties and economic benefits of wolfberry orchards on the Tibetan Plateau

Water scarcity and low soil fertility severely constrain crop growth and sustainable agricultural productivity on the Tibetan Plateau. Organic amendments and ridge–furrow mulching system (RFMS) are widely used to improve soil moisture, soil structure, and crop production in arid and semi-arid areas. However, their combined effects on soil physicochemical properties and economic benefits of wolfberry (Lycium barbarum L.) on the Tibetan Plateau remain unclear. A two-year field experiment was undertaken to evaluate the combined effects of organic amendments and RFMS on soil water, soil structure, soil saturated hydraulic conductivity, soil organic carbon (SOC), total nitrogen (TN), and economic benefits on wolfberry. Four cultivation practices were established: traditional flat plot with mulching (FP), traditional flat plot with mulching and organic amendment (FPOA), ridge–furrow planting with mulching (RF), and ridge–furrow planting with mulching and organic amendment (RFOA). The organic amendment and RFMS treatments had higher soil water storage (SWS) and soil desiccation index (SDI) than the FP treatment in both growing seasons, especially at 20–60 cm soil depth. In addition, organic amendment significantly decreased soil bulk density by 6.4% and increased soil saturated hydraulic conductivity by 16.8% in the 0–60 cm soil layer, respectively, and improved the proportion of larger soil aggregates (0.02–2 mm) by 10.8% in the 0–40 cm soil layer. Furthermore, the RFOA treatment significantly improved SOC and TN contents at 0–60 cm soil depth by 47.7% and 19.4%, respectively, relative to FP. The measured soil properties were highly correlated with wolfberry yield and water use efficiency over 2 years. In particular, the RFOA treatment had higher crop yield and economic benefit than the other treatments due to the more favorable soil environment. Therefore, the RFOA treatment could be a sustainable and efficient cultivation practice for alleviating drought stress, improving soil properties, and increasing economic benefit on the Tibetan Plateau.

Response of surface-soil quality to secondary succession in karst areas in Southwest China: Case study on a limestone slope

Karst areas are fragile ecological environments facing serious soil quality problems. It is crucial to understand the surface-soil quality for ensuring the secondary succession of vegetation. In this study, four plots located on the same hill slope were selected, representing the four secondary succession stages of arable land, grassland, shrubs, and secondary forest, respectively. The surface-soil quality during secondary succession is assessed using the minimum dataset method. The results show that secondary succession decreased soil bulk density and total potassium content (P < 0.05), whereas soil organic matter, saturated hydraulic conductivity, overall porosity, and total nitrogen increased (P < 0.05). However, pH and capillary porosity are relatively stable. Non-capillary porosity and total phosphorus content first decreased and then increased. In addition, the mean soil quality indices increased and the difference in surface-soil quality between stages decreased with vegetation succession (P < 0.05). Improvement in surface-soil quality is most obvious in the early stages of secondary succession, and natural vegetation restoration can solve the land degradation problem. This study is not only helpful in understanding the changes in surface-soil quality during the secondary succession but also provides a theoretical basis for selecting ecological restoration methods in karst regions.

Migration characteristics of soil salinity in saline-sodic cotton field with different reclamation time in non-irrigation season

Cultivation after converting saline and alkaline wasteland to agricultural land is usually accompanied by accelerated soil salinization. There is general agreement that freezing-thawing process plays a crucial role in soil salinization in mostly cold-arid agricultural areas, which leads to the impoverishment of soil productivity. To investigate the migration characteristics of soil salinity in saline-sodic cotton field with different reclamation time in non-irrigation season, we examined the soil bulk, total porosity, and spatial and temporal migration of soil salinity in winter in an oasis agroecosystem of northern Xinjiang, China. Experimental plots include a saline-alkali wasteland as control and cotton fields under four age categories (cultivation start years were 1998, 2006, 2008, and 2012, respectively). The results showed that converting saline-alkali wasteland to cotton land significantly decreased soil bulk density but increased total soil porosity, especially at 0–40 cm. Conversion significantly decreased soil salinity at 0–200 cm soil depths, with a greater decrease in cotton land after relatively longer time of cultivation. After freezing-thawing process, soil bulk density decreased 4.87% on average, and total porosity increased 5.98%. Soil salt dynamics showed that there were two stages in salt accumulation. Firstly, soil salt storage increased at 0–100 cm depth but decreased at 100–200 cm depth during freezing period; Secondly, rapid increase of salt storage appeared at late thawing period. In addition, salt accumulation positively correlated to initial salt content and bulk density, but negatively correlated to total porosity. At springtime, cotton land with short-term cultivation was desalination comparing with pre-freezing, but salt accumulation occurred after long-term cultivation. These results highlighted that long-term cultivation with mulched drip irrigation decreased soil salinity in the 0–200 cm soil profiles, but freezing-thawing process induced soil salinization which poses a potential risk to agricultural sustainability.

Effects of bacterial inoculation on soil physical properties

This study was carried out to investigate the impacts of bacterial inoculation on texturally different soil samples under greenhouse conditions. Sandy loam (SL), clay loam (CL), and clay (C) textured soils were inoculated with Bacillus arenosi K64 (B. arenosi), Bacillus megaterium M3 (B. megaterium), and Bacillus subtilis OSU 142 (B. subtilis) isolates and then incubated at 5 different periods [I (20 days), II (40 days), III (60 days), IV (80 days), and V (100 days)]. Soil physical properties, including bulk density, total porosity, mean weight diameter, and intrinsic permeability, were evaluated. It was found that bacterial inoculation caused a decrease in soil bulk density and intrinsic permeability, increased porosity, and mean weight diameter. In sum, the most effective results were noticed in the soils inoculated with B. subtilis.

ПРАКТИЧЕСКОЕ ПРИМЕНЕНИЕ ОСАДКА СТОЧНЫХ БЫТОВЫХ ВОД НА ПРИМЕРЕ ВОЗДЕЛЫВАНИЯ САФЛОРА КРАСИЛЬНОГО

Purpose: to study the main indicators of sewage sludge in the town Volzhsky and the possibility of its practical application on farmlands. Materials and methods. The object of research is sewage sludge from waste treatment plants of the town Volzhsky, Volgograd region. The chemical composition of sewage sludge was studied under laboratory conditions. Field experiments were laid in accordance with generally accepted methods. Results and discussions. Experimental studies have determined that high concentration of nitrogen (3.3 %), phosphorus (4.27 %), potassium (0.31 %) was noted in the sewage sludge, the organic matter content was 32.0 %. The water extract analysis data indicate a high concentration of calcium cations (33.25 mmol/100 g of soil) and magnesium (14.25 mmol/100 g of soil), as well as sulfate anions (5.80 mmol/100 g of soil). Heavy metals are present in the sludge, but their amount is much lower than the maximum permissible concentration. When testing sewage sludge in the field, it was found that, a decrease in soil bulk density to 1.10 t/m cub. is achieved in combination with chisel tillage. (dose of sewage sludge is 5 t/ha) and up to 1.07 t/m cub. (dose of sewage sludge is 10 t/ha). The data analysis on the safflower yield shows that the processed sewage sludge application increases the yield of safflower seeds in all years of research. The variant of combined action of sludge at a dose of 10 t/ha and chisel tillage turned out to be preferable, which made it possible to increase the safflower yield to 1.51 t/ha on average over the years of research. Conclusions: under the arid conditions of Volgograd region, it is advisable to use deep chisel tillage in combination with sewage sludge at a dose of 10 t/ha in order to increase the productivity of safflower and reduce the bulk density.

Short-term soil physical responses to grazing and cover crops in an integrated crop-livestock agroecosystem

Cover crops (CCs) and grazing play critical roles in the successful implementation of integrated crop-livestock systems (ICLSs) because they can have a direct impact on soil functions. The present study was conducted to assess the short-term impacts of CCs and grazing on soil physical and hydrological properties. Two sites (Northern-Brookings and Northwestern-Brookings) were established in 2016 and 2017, respectively, in South Dakota, United States. The specific objective was to evaluate the impact of CCs and grazed CCs under oat (<i>Avena sativa</i> L.)/CCs–corn (<i>Zea mays</i> L.) rotation on soil physical and hydrological properties. Study treatments included (1) legume-dominated CC (LdC), (2) cattle-grazed LdC (LdC+G), (3) grass-dominated CC (GdC), (4) cattle-grazed GdC (GdC+G), and (5) no CC and no grazing (NC). After two to three years of management, CCs and grazing did not impact soil organic carbon (SOC) and total nitrogen (TN) stocks, and their values at approximate depth of 0 to 20 cm ranged from 50.9 to 60.6 Mg C ha⁻¹ and 3.65 to 4.92 Mg N ha⁻¹, respectively, among the treatments at each site. Cover crops decreased soil bulk density (ρ_b) at 0 to 10 cm and 10 to 20 cm depths and, in general, increased soil water retention (SWR), total porosity, and quasi-steady infiltration rate (Northern-Brookings only) compared to the NC. Cattle grazing of CC generally increased ρ_b and reduced SWR and porosity compared with the ungrazed CC but not to the often-perceived detrimental levels. Our findings showed that CCs can improve some aspects of soil physical health in the short term and that grazing of CCs and crop residue did not cause substantial physical damage to the soil under the conditions of these experiments.

Immediate and long-term effects of tillage practices with crop residue on soil water and organic carbon storage changes under a wheat-maize cropping system

Reasonable tillage management benefits soil structure optimization and agricultural sustainability. However, the differences of immediate (i.e. changes between post- and pre- tillage) and long-term effects (i.e. changes between treatments after certain years) under different tillage practices is often neglected. This study involved a 16-year field experiment including three tillage practices (plow tillage, PT; subsoiling tillage, ST and rotary tillage, RT) and two crop residue management practices (no residue return and all residue return). Those immediate and long-term effects on soil physical properties and soil organic carbon were investigated. For the immediate effects after tillage, the soil water storage under PT, ST, and RT decreased by 5.8%, 4.0%, and 3.2%, respectively; while those under residue return and no residue return decreased by 3.9% and 4.6%, respectively. Under the same conditions, ST was more beneficial to reduce soil penetration resistance. The soil bulk density post-tillage was significantly lower than that pre-tillage at 0–10 cm soil depth, meanwhile the soil bulk density at 10–40 cm soil depth was generally decreased after tillage practice under ST treatment. For the long-term effects, the penetration resistance at 10–50 cm soil depth and the soil bulk density at 10–30 cm soil depth were lower under the ST treatment than those under PT and RT treatments. Additionally, residue return was beneficial for soil water storage, soil bulk density, and soil organic carbon storage. Overall, both for the immediate and long-term effects, subsoiling tillage with residue return significantly increased soil water storage, total porosity, soil organic carbon storage and crop yields, while decreased soil bulk density and penetration resistance.

Improving plant available water holding capacity of soil by solid and chemically modified biochars

We investigated the possible effects of solid biochar and chemically modified biochars (biochar-based nanocomposites of magnesium and manganese, modified biochars with H2O2, KOH and H3PO4) on changing water retention in a silty loam texture soil. All biochar treatments were applied at a rate of 25 g biochar kg−1 soil. Results showed that application of solid biochar and especially chemically modified biochars decreased soil bulk density and saturated hydraulic conductivity, but noticeably improved water holding capacity and plant available water holding capacity in soil. The highest improvements in soil water holding capacity and plant available water holding capacity were achieved under biochar-based nanocomposites of magnesium and manganese and H3PO4 modified biochar treatments. In general, soil treatment with chemically modified biochars caused a better effect than solid biochar in increasing water availability within soil by decreasing saturated hydraulic conductivity.

Effect of integrated fertilizer application on soil properties and tef (Eragrostis tef [Zucc] Trotter) yield on Vertisols of Northwestern Ethiopia

Low soil fertility has become a serious constraint affecting agricultural productivity and food security in North-western Ethiopia. A field experiment was conducted to examine the effects of integrated use of compost and mineral fertilizer on soil properties and tef (Eragrostis tef [Zucc.] Trotter) yields for two years during 2018 and 2019 cropping seasons. The field experiment was arranged in a factorial combination of three rates of Urea/NPSB (0/0, 62.5/75 and 125/150 kg ha−1) and three rates of compost (0, 5 and 10 t ha−1) laid out in randomized complete block design (RCBD) with three replications. Results showed that combined use of compost and mineral fertilizer significantly (p < 0.05) increased soil pH, soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), available sulfur (AS) and exchangeable bases but significantly (p < 0.05) decreased soil bulk density (SBD) compared to sole mineral fertilizer application and the control. Furthermore, application of 10 t ha−1 compost combined with 125/150 kg ha−1 Urea/NPSB gave the highest tef dry biomass (8.81 t ha−1) and grain yield (2.40 t ha−1). The economic analysis results also revealed that the highest net benefit (45,761 Birr ha−1) was achieved from the same treatment which was considerably greater than the highest rate of sole mineral fertilizer (37,228.5 Birr ha−1), the highest rate of sole compost (6656 Birr ha−1) and the control (5391 Birr ha−1). We concluded that integrated fertilizer application enhances soil fertility, crop yields and generates better income over individual addition of fertilizers.

Restoring closed trails in the Sonoran Desert: interactions of seed timing, seed source, and ripping

Ecological restoration is a promising way to improve ecological function, habitat connectivity, and esthetic values for recreation. However, effective restoration practices for arid environments remain elusive. To help fill this knowledge gap, we tested ripping soils, seed mixtures, including adding native seed bank topsoils, and seeding timing on permanently closed trails at sites in the Sonoran Desert, Arizona, U.S.A. Ripping had the desired effect of decreasing soil bulk density and increasing infiltration and water‐holding capacity of closed trails. However, ripping increased non‐native plant cover by 14.1% and decreased native plant cover by 2.2% by the fourth year of the study. Seed mixtures performed best when planted before the winter rains compared to before the summer monsoon, but only 3 of the 10 seeded species persisted across years. The seed bank topsoil application was most effective at increasing native species richness in the first year and yielded an average of two more plant species than unseeded plots over the 4‐year experiment, but only in unripped plots. By the fourth year of the study, plots on the ripped and unripped closed trails had similar levels of plant cover and richness as the nearby native plant community, even in unseeded plots, suggesting that in small disturbed areas, the plant community has the potential to regenerate without inputs if disturbance is removed.

Conservation tillage rotation enhanced soil structure and soil nutrients in long-term dryland agriculture

Conservation tillage has been proposed as an effective way to conserve soil water in dryland agriculture. However, long-term continuous mono-tillage including conservational and conventional tillage has been proved to have limited improvements or some defects on soil structure and nutrients enhancement. Combining different tillage practices in a rational rotation that adapts to the cropping system may optimize the advantages and improve the potentials of mono-tillage practices. Soil porosity, aggregates, water, organic carbon, nitrogen and crop yield were investigated in a ten-year (2007–2016) long-term conventional with conservation tillage rotation experiment which contained four tillage systems, NT (no-tillage), ST (subsoiling), CT (conventional tillage), and NCS rotation (no-tillage, conventional tillage and subsoiling rotated annually) in a dryland field to assess the soil pore system, aggregates, nutrients content and productivity. Compared with three mono-tillage systems (NT, ST and CT), the NCS rotation significantly decreased soil bulk density by 3.8–8.4 % and increased soil porosity by 3.2–6.7 % (P < 0.05) after ten years. NCS rotation increased soil capillary porosity by 9.7–36.3 %, reduced inactive porosity by 4–8.1 % when compared to continuous mono-tillage (NT, ST and CT), optimized soil porosity distribution at 0−60 cm soil depth till the tenth year. Meanwhile, compared with mono-tillage, NCS rotation improved soil macroaggregates content (0.25–5 mm) by 35.2–46.4 % and resulted in 40.3–113 % higher macroaggregates content than ten years before at 0−40 cm soil depth (P < 0.05). As the experiment continues, soil organic carbon (SOC) and nitrogen (TN) at different tillage systems accumulated at rates of 1.65−2.01 Mg ha−1 year−1 and 0.14−0.21 Mg ha−1 year−1, respectively, NCS rotation resulted in the highest soil nutrients accumulation (SOC: 57.98 Mg ha−1, TN: 6.40 Mg ha−1), better soil nutrients distribution and suitable C/N (9.01) for crop growth and soil enhancement. Additionally, NCS rotation conserved more soil water in fallow period (394 mm) and during crop growth season (winter wheat: 352 mm, spring maize: 384 mm), produced higher winter wheat (5169 kg ha−1) and spring maize yield (8251 kg ha−1). The long-term rotational research showed that NCS rotation optimized soil structure (soil porosity, soil aggregates) and enhanced soil nutrients (SOC, TN), provided better soil conditions for crop production in dryland rain-fed farming agriculture.

Rhizosphere soil properties, microbial community, and enzyme activities: Short-term responses to partial substitution of chemical fertilizer with organic manure

The partial substitution of chemical fertilizers with organic manure has positive effects on crop productivity and sustainable development. Nevertheless, few studies have focused on major grain crops. Herein, we report the short-term effects of the partial substitution of chemical fertilizers with organic manure on the physicochemical properties, microbial community, and enzyme activities in the rhizosphere soil of a maize (Zea mays L.) field. A decrease in soil bulk density, pH, and electrical conductivity, concomitant with an increase in soil urease, invertase, and alkaline phosphatase activities, and a high level of nutrients were observed in organic manure-treated soil. The influence of the organic substitution treatment on bacterial diversity was greater than that on fungal diversity, particularly on alpha diversity. Among dominant bacterial phyla, Actinobacteria abundance changed the most, with significantly increase under organic manure treatment. In turn, among fungi, only Ascomycota responded substantially to organic substitution. Binding spatial ordination analysis revealed that relative soil water content and soil organic carbon, and nitrate and total nitrogen contents had a stronger effect on bacteria and fungi, respectively, than any other soil physicochemical property. Additionally, the changes in bacterial and fungal communities influenced soil enzymatic activities. Moreover, partial least squares path model revealed that soil physicochemical properties indirectly affected soil enzymatic activities by their direct effects on microbial (both bacteria and fungi) community. Overall, our results indicate that the substitution of chemical fertilizers by organic manure changed the composition of the soil microbial community, and that the effects of the substitution were more significant on bacteria than on fungi.

Miombo conversion to monoculture tree plantations: Changes in soil properties

AbstractMonoculture plantations replacing native woodlands are increasingly common globally. In Mozambique, vast miombo* woodlands have been replaced by single‐species plantations. Studies on the effect of replacing native woodlands by single‐species tree plantations on soil properties are abundant; however, those focused specifically on the replacement of miombo and considering a longer time since replacement and covering different growth stages are scarce. This article aimed at assessing the effects of the conversion of miombo to monoculture on soil properties and studying the effect of species planted, plantation age, and rotation on soil capacity to store carbon (C) and nitrogen (N). Plantations established in soils formerly covered by miombo were compared to the remaining original miombo with regard to soil properties. The effect of species planted, plantation age, and rotation on soil properties was examined using the three‐way ANOVA, followed by Tukey's test. Miombo conversion to plantations led to an increase of up to 66% of soil organic C (SOC) and 77% of total N (STN) and a decrease in soil bulk density (BD) of up to 16%. The replacement of the first‐ by second‐rotation plantations led to a decrease of up to 38% in SOC and STN and an increase of up to 32% in BD. BD decreased with plantation age; SOC and STN stocks tended to increase: 60 years after the replacement of miombo by plantations, SOC and STN increased by up to 88%. Changes in soil properties due to the replacement of miombo by monoculture were mainly driven by the species planted.* a sparse open deciduous woodland characteristic of dry parts of eastern Africa

Yield and yield components of maize and soil physical properties as affected by tillage practices and organic mulching.

Maize (Zea mays L.) is an important grains cereal crop. Lots of farmers using tillage and mulching practices influence the final yield, to maintain up with the growing demand for food, fuel and feed. Field experiments were conducted to investigate the effects of tillage practices (i.e. conventional tillage CT, reduced tillage RT, deep tillage DT) and wheat straw mulching (i.e. no mulch and wheat straw mulch of 4, 8 and 12 Mg ha−1, SM0, SM1, SM2 and SM3 respectively) on the growth, yield and yield components of maize and some of soil physical properties. The results showed that compared with RT, DT and CT decreased soil bulk density, as well as led to increase soil water content. Application of mulch treatments increased soil water content. DT and CT have been associated with greater plant height, yield components, grain and biomass yield than RT treatment. Plant height, yield components, grain and biomass yield as well as soil water content increased following mulching treatments. Mulching treatment of SM2 had the largest positive effects on maize yield. DT and CT that have potential to break the compacted zone in soil leading to a better soil environment and crop yield. The application of wheat straw mulch could be an efficient soil management practice for corn production in arid subtropical climate region.

Bentonite effects on soil physical properties and millet yield components in a semi-arid region in China

Soil structure plays a critical role in agroecosystems because it controls soil air and water capacity, nutrient availability, and crop root growth. A field experiment was conducted to evaluate the effect of bentonite on soil relative water content, soil cone penetration resistance, soil bulk density, aggregate size distribution, and millet crop yield components in a semi-arid region in northern China from 2011 to 2015. Treatments consisted of six bentonite rates (0, 6, 12, 18, 24, and 30 Mg·ha−1) applied only in the initial year. Addition of bentonite significantly increased soil relative water throughout the profile (0–60 cm) and aggregates in 0.25–2 mm class in 0–40 cm depth; it significantly decreased soil bulk density, soil cone penetration resistance, and aggregates in 0.053–0.25 mm class in the 0–40 cm depth. All of the bentonite treatments significantly increased 1000-kernel weight and panicle number up to 16% and 33%, respectively, but did not affect kernels per spike. Treatment with 24 Mg·ha−1 bentonite achieved the greatest effect on all the soil physical parameters and crop yield components averaged over all years; the highest application rate (30 Mg·ha−1) had an increasing effect over time. This study indicates that application of bentonite improves soil health in sandy-loam soil in a semi-arid region, and thus it would help promote sustainable agriculture development in regions with similar soil and climate.

Hardwood mixture enhances soil water infiltration in a conifer plantation

Soil hydraulic properties affect soil infiltration capacity. Limited information is available about how hardwood mixture influences water infiltration in conifer plantations through its effects on soil hydraulic properties. We evaluated how, and to what extent, infiltration rates were affected by abiotic and biotic conditions along gradients of abundance and diversity of hardwoods and abundance of understory plants in nine stands representing three replicates of three different thinning intensities (unthinned [Control], 33% thinning [Weak], and 67% thinning [Intensive]) in a Cryptomeria japonica (Thunb. ex L. f.) D. Don plantation. Correlation analyses and a structural equation model (SEM) indicated that infiltration rates were enhanced by hardwood mixture (i.e., abundance and species richness of hardwoods) and abundance of understory plants, via increases in the fine root density and accumulation of broadleaf litter, because the fine root density decreased soil bulk density and accumulation of litter increased the porosity and both of which greatly improved the soil hydraulic conditions. In the Intensive treatment, complementarity effects stemming from vertical partitioning of resource acquiring organs (i.e., leaves) among species might have increased accumulation of broadleaf litter. If increased volumes of broadleaf litter promote increased earthworm abundance, earthworms may in turn cause higher porosity, because the burrowing activity of earthworms increases the number of macropores. Consequently, hardwood mixture with abundant understory plants promotes increased infiltration rates. Our results demonstrate that intensively thinned stands with an abundance and diversity of hardwoods, including broadleaf understory plants, can absorb and store more water compared to lightly thinned stands with only understory plants, owing to increased soil infiltration capacity. Our results point to the importance of hardwood mixture in enhancing ecosystem functioning in conifer plantations.

Soil management practices in coffee-based agroforestry systems within Universitas Brawijaya Forest impact on maintaining soil carbon stock

Farmer fertilization practices is one of effort on climate change mitigation and determine environmental services of agroforestry systems especially soil carbon stocks. The research aimed to assess soil carbon stock in smallholder agroforestry systems within Universitas Brawijaya (UB) Forest, East Java. The study was conducted on two different types of fertilizer application (e.g., organic, mixed organic and inorganic fertilizer) with three different doses of organic fertilizer (e.g., 5, 10, 15 kg tree−1) and 3 replications of each, totalling 18 plots. At each plot, soil sample was collected at fertilized and unfertilized areas with a depth 0-20 cm and 20-40 cm, then measured total organic C, soil bulk density, soil pH, and soil carbon stocks. Application of mixed fertilizer had 19-42 % lower of soil organic C as compared to those in application of organic fertilizer, resulted in decrease of soil carbon stock around 15-41 % at a depth 0-40 cm. In addition, the increases dose of organic fertilizer application up to 15 kg tree−1 decreased soil bulk density at 0-20 cm depth of soil around 8-10% as compared to dose 5 and 10 kg tree−1. Our study suggested to optimize fertilization practices for maintaining soil fertility and its relationship to coffee production.

Effects of thinning on soil nutrients in a chronosequence of Chinese fir in subtropical Chinaforests

Thinning is a common silviculture technology in forestry, but there is considerable uncertainty about the changes of soil nutrients due to thinning practice in different aged forests. The influence of light thinning (reduction of 20% of stand density) on soil organic carbon (SOC) and other mineral elements (N, P, K, Cu, Fe, Zn, Mn and S), as well as soil pH and soil bulk density were investigated in 6-, 13-, and 23-year-old growth stands of Chinese fir forests in subtropical China. Six 10m ×10m plots (three thinning and three non-thinning plots) were set up in each aged forests. Soil samples were taken from different soil layers from these plots for nutrient analysis. Results showed that SOC increased 59.4, 48.9, and 62.0% in topsoil layer (0-30 cm) in 6, 13, and 23 year-old growth stands, respectively when compared to the control, and the content of N increased by 20.5, 44.6, and 54.1% corresponding after two year post-thinning. In the thinned forests, soil P slightly increased at 6- and 23 year-old growth forests dude to microclimates were improved, and K decreased because of leaching. The response of micronutrients Cu, Fe, Zn and Mn to thinning varied in all examined Chinese fir forests. Thinning decreased soil bulk density and soil pH in 6 and 23 year-old growth stands. Our study provided scientific references for sustainable management of soil nutrients under forest operations in Chinese fir forest ecosystem in subtropical China.