Soil Fertility Potential Research Articles

РОЛЬ УГЛЕРОДА И КРУГОВОРОТЫ НА ЕГО ОСНОВЕ КАК ПРЕДПОСЫЛКИ СОВЕРШЕНСТВОВАНИЯ СИСТЕМЫ МОНИТОРИНГА ПЛОДОРОДИЯ ПОЧВ

The most important role in ensuring soil fertility is played by biological processes, and this, above all, the cycles of the main nutrients of plants, animals and microorganisms. Cycles play an important role in the biosphere, providing direct and inverse links in the chains of the agro-ecological system, while maintaining the integrity of the biosphere. To monitor soil fertility it is necessary to determine (find) an integral index and its cycle, which most objectively reflects this property of the soil. Such an indicator, according to our research, is the quantity and qualitative composition of organic matter in the soil, which mainly consists of plant biomass, as well as micro and animal organisms. From the standpoint of chemistry, carbon is a part of the organic matter of the soil in the form of a huge amount of biochemical compounds containing virtually the entire table D.I. Mendeleev, but only about 30 elements (organogenic) have fixed amount and are found in organisms all the time. At the same time, the ratio of organogenic elements in the soil is different, more concentrated, rather than in the crust, established by geochemistry. In this regard, we found that the main indicator of soil fertility (having a closer correlation with it and integrally reflecting it) can be the content and balance of organic matter in it, the activity of which determines the effective and potential soil fertility. As an indicator of the cycle of organic matter it is necessary to use the carbon cycle in the soil on which all organic matter in the biosphere is built. The role of many biochemical carbon compounds in the evolution of living and soil fertility remains is to be seen.

Indicators of optimal soils conditions for crop growing and preserving soil fertility in Rostov region and North Caucasus under irrigation conditions

The tasks of agrotechnical and land-reclamation techniques in creating favorable conditions for the agricultural crops growth are determined. Maintaining high soil fertility and good land-reclamation. Soil fertility model with optimal indicators providing a combined expanded reproduction of soil fertility is proposed. Main indicators of potential soil fertility are considered. Indicators and properties of soils are captured, the relationship between plant productivity and soils quality is made. The adverse soil properties of the North Caucasus that include alkalescency and alkalinity are determined. Complex of agrotechnical and land-reclamation techniques for improving adverse soils is proposed.

Crop Structure Changes Altered the Cropland Nitrogen Balance between 2005 and 2015 on the Sanjiang Plain, China

Nitrogen (N) budgets have been computed in many countries at various scales to improve understanding of N-balance characteristics and to assess the environmental pollution risks of applying chemical fertilizer N. However, dynamic characteristics, driving forces, and potential soil fertility consequences related to cropland N balance have seldom been discussed, especially in regions with highly fertile soils and low N-use intensities. This study investigated the temporal and spatial characteristics of N balance, and the impact of agricultural development on the agro-ecosystems of the Sanjiang Plain, one of the largest producers of commodity food grains in China. County-level agricultural statistics at five-year intervals were used to calculate agricultural N balances, N surplus intensity, and N-use efficiency between 2005 and 2015. Agricultural development has brought about continual increases in cultivated land area, consumption of chemical fertilizers, and nitrogen use efficiency (NUE). Nitrogen surplus intensity decreased from 65.0 kg/ha in 2005 to 43.5 kg/ha in 2010, and to 22.2 kg/ha in 2015. However, NUE was >90% in 13 counties in 2015, and in 11 counties in 2010. In contrast, only 5 counties had NUE above 90% in 2005, which indicates that N from the soil was used by crops and soil fertility was gradually decreasing. The percentage change of crop area, namely, the increase in maize area percentage, contributed significantly to the increases in NUE. A judicious management of fertilizers that meets the nutrient needs of the crops and ensures agricultural sustainability on the Sanjiang Plain is therefore essential. The findings of this study emphasize the importance of assessing the impact of crop structure adjustment on soil fertility and nitrogen balance during agricultural development.

Estimation of effectiveness of usage of liquid organic fertilizer in the context of rational land use: a case study of Ukraine

The purpose of the article – to perform comparative analysis of the economic effectiveness of the 10 samples of organic fertilizer of pig farm, bio humus “Humivit” and mineral fertilizers (Nitroamofoska, ammonium nitrate, carbamide) on the example of oats. The study used the following methods: abstract-logical, cash-analytical, cash-equivalent, expert, monographic. The research was done in Ukraine. The results of the comparative analysis of economic effectiveness of the 10 samples of organic pig fertilizer, bio humus “Humivit” and mineral fertilizers (Nitroamofoska, ammonium nitrate, carbamide) in the example of oats on the green mass show that the use of organic fertilizers sample number 1, 2, 3, 4, 5, 6, 10 is an economically effective, while organic fertilizers of sample number 7, 8, 9 are economically inefficient. By the main indicators of economic effectiveness (coefficients of payback, conditional additional profit, level of profitability) organic fertilizers sample number 1, 2, 3, 4, 5, 6, 10 have significant competitive advantages over the studied brands of mineral fertilizers and bio humus “Humivit”. The use of organic pig fertilizers, except the sample number 8, in economic terms for the impact on potential soil fertility is more effective than bio humus “Humivit”. The most significant economic benefits for the impact on potential soil fertility are samples of organic fertilizers pig number 1, 5, 10, whose application generates the lowest cost price of humus. The element of novelty is that with using the author’s scientific and methodical approach it was conducted the estimation of economic effectiveness of the liquid organic fertilizer of pig farm for the impact on potential soil fertility.

Identifikasi Mineral Pembawa Hara untuk Menilai Potensi Kesuburan Tanah

Soil minerals are very important for plants and can be use to assess the potential of soil fertility. This study aims to assess the potential of soil fertility based on mineral identification in Banggae and Eastern Banggae Subdistrict, Majene District, West Sulawesi Province. The method used in this research is descriptive quantitative, by identifying the minerals in the parent material and soil from thin section using polarizing microscope, quantification method for minerals percentage, and classified of nutrient potential with percentage of mineral content reduced by the percentage content of the quartz. The results showed that the dominant mineral found in the parent material and soil are pyroxene, plagioclase, hornblende, biotite, calcite, quartz and opaque, but the size of mineral are smaller than in the parent material. Potential of nutrients generated in the form of weatherable minerals are biotite, calcite, plagioclase, hornblende and pyroxene containing elements such as Mg, Ca, K, Fe and Na. Potential soil fertility in parent material currently on the moderate criteria (48% to 70%), while on the soil with middle criteria (48% to 70%) in P1L1, P2L1, P4L1, P8L1, P9L1, P10L1, P11L1 and P11L2 and good criteria (73% to 79%) in P3L1, P3L2, P4L2, P5L1, P5L2, P6L1, P7L1 and P9L2. Potential nutrient contained in the mineral is not available for plants, because it has not been supported by external factors such as the low availability of water. This is due to the climate condition especially rainfall in research area is in the range of 949.0 to 2557.1 mm/year with an average annual rainfall of 1608.0 mm/year.

Effect of living cells of microalgae or their extracts on soil enzyme activities

ABSTRACTThe enzymatic activity of the soil and potential plant growth can both be affected by the addition of different substances, such as biostimulants. The final objective of this work was to evaluate the effect of Chlorella vulgaris, Scenedesmus quadricauda or their extracts applied directly into the soil, by monitoring the complex soil-microorganism-plant system. Experiments were conducted in pots using agricultural soil and tomato plants in a growth chamber at 25 ± 2 °C illuminated by artificial light with a 16-h photoperiod. The soil biological activity was analyzed by monitoring fluorescein diacetate hydrolysis, dehydrogenases, acid and alkaline phosphomonoesterase and urease activities. Dry weight and chlorophyll index values of tomato plants were also investigated. Results showed that both the microalgae and their extracts positively affected soil biological activity by increasing values of the biochemical index of potential soil fertility (Mw) both in cultivated and uncultivated soils. The highest Mw value was reached in cultivated soil treated for 11 days with the lower concentration of S. quadricauda extract (Mw 9.47). All treatments significantly increased the growth of tomato plants with respect to untreated soil. These results are very promising with a view to improving soil biological activity as well as increasing plant growth.

Degradation of soil nutrients and slow recovery of biomass following shifting cultivation in the heath forests of Sarawak, Malaysia

Heath forests which are tropical forests on sandy soils are widely distributed in Borneo and provide many ecosystem services, such as carbon storage and non-timber forest products. Over the past several decades, such forests have been disturbed by non-traditional shifting cultivation, which is usually conducted in unsuitable land with short fallow duration. Anthropogenic disturbances in forests growing on sandy soils that have low nutrient retention capacities may promote further reductions in soil fertility. Long-term monitoring of soil nutrients and biomass accumulation is rare in degraded tropical rainforests growing on sandy soils despite the known negative effects of non-traditional shifting cultivation practices on soil fertility, vegetation and biomass recovery, and the growth of trees planted to rehabilitate forests. The objective of the current study was therefore to elucidate changes in soil fertility and biomass recovery potential in degraded forests on sandy soils in Borneo. We monitored soil nutrients and chemical properties in fifty-four 12 × 12 m plots located on different topographical positions along upper and lower slopes. Samples were collected in plots aged 7 and 14 years after abandonment of shifting cultivation. The biomass of secondary forest trees in all plots 12 years after the abandonment was also measured to determine the relationship between biomass accumulation and changes in soil nutrients. We found that soil pH and cation exchange capacity, and the concentrations of most nutrients, including nitrogen, magnesium, and phosphorus, had decreased significantly 7–14 years after abandonment; biomass accumulation in the plots was also limited 12 years after abandonment (<0.8 Mg ha−1 year−1). These changes in soil traits within the study plots were similar regardless of topographical position, and the changes were not related to the amount of biomass. Soil nutrients in the plots may have leached out as a result of removal of thick root mats in the surface soil, high sand content, and large amounts of rainfall in the area rather than uptake by recovering trees. These results indicate that it may be difficult to recover soil fertility on steep slopes in sandy soil conditions because of high leaching rates and erosion when the soil surface layer is destroyed by shifting cultivation. It is therefore important to carefully manage shifting cultivation practices in tropical forests on sandy soils in Borneo.

THE DYNAMICS OF MENSURATIONAL INDICES AND THEIR SHORT-TERM PREDICTION IN BIRCH-PINE STANDS UNDER A2 TYPE CONDITIONS (FRESH INFERTILE PINE SITE TYPE)

Здійснено моделювання основних лісівничо-таксаційних показників для березово-соснових деревостанів в умовах свіжого соснового бору. Використання деревом площі живлення у повному обсязі є верхнім обмеженням росту у фіксований момент часу. Досягнення максимальних біометричних показників дає змогу дереву найкраще використовувати потенційну родючість ґрунту. З погляду теорії систем, деревостан, що досягає стану динамічної рівноваги, називають оптимальним, який характеризується найвищою продуктивністю. Вплив природних чинників на формування деревостанів зумовлює природний, без антропогенного втручання, розвиток лісостанів, за якого ріст і розвиток дерев забезпечується саморегуляцією. Внаслідок цього формуються динамічно врівноважені,максимально продуктивні біологічні системи. Докладний аналіз процесів росту і розвитку деревостанів у конкретних умовах дає змогу визначати моделі короткотермінового прогнозу окремих показників деревостану для розрахунку інтенсивності та повторюваності доглядових рубань. Встановлено, що збільшення обсягу вирубуваноїдеревини сосни веде до зменшення запасу та істотного збільшення середнього діаметра кращих дерев. Результати прогнозу отримано для інтенсивності доглядових рубань в межах 16–30 % від запасу деревостану на контрольній пробній площі. Отримані динамічні ряди основних таксаційних показників соснових деревостанів у свіжому сосновому борі запропоновано використати як теоретичну основу для подальшого проектування доглядових рубань та формування березово-соснових насаджень із поліпшеною товарною структурою.

Accumulation of SOC under organic and no-fertilizations, and its influence on crop yields in Tanzania’s semiarid zone

ABSTRACT Introduction: To estimate differential accumulation of soil organic carbon (SOC) and its ecological significance is very important to smallholder farmers in the Tanzania’s semiarid areas. This study investigated the accumulation of SOC and other important soil nutrients under organic and no-fertilizations, and correlated SOC with crop yields. Using data from long-term experimental study sites of semiarid in Tanzania, we estimated SOC accumulation in different soil treatments and depths where a total of 128 soil samples were collected at the depths of 0–20 cm and 20–40 cm from two villages (sites) with organic fertilization and no-fertilization treatments. Sites under organic fertilization were defined as those which have received manure fertilization for more than 5 years on continuum basis. Outcomes: The accumulation of SOC was significantly greater in soils under organic fertilizations (1.15 and 0.80 MgC ha−1 at soil depth and 20–40 cm) and decreased with increasing soil depths. Similarly, TN and P decreased from 0.40 and 2.40 Mg (0–20 cm) to 0.16 and 2.10 Mg (20–40 cm), respectively. Other important soil nutrients such as calcium (Ca2+), potassium (K+), magnesium (Mg2+), and sodium (Na+) had similar pattern. In addition, soil bulk density was less under organic fertilization (1.1 g/cm3) than under no-fertilization (1.2 g/cm3) and it increased with soil depths. Correspondingly, the crop yields were significantly higher (1.6 tn ha−1) under organic fertilizations than (0.6 tn ha−1) under no-fertilizations indicating that crop yields were significantly affected by SOC. Discussion: Organic fertilization i.e., especially cattle manure in the area has considerable fertility potential. To optimize soil fertility potential, we need to consider such kind of fertilization from household to national level. Conclusion: Our results demonstrated that manure application was the best fertilization method for improving soil fertility in most croplands of Tanzania’s semiarid areas, especially in this era of climate change scenarios.

Predicting the spatial and temporal dynamics of species interactions in Fagus sylvatica and Pinus sylvestris forests across Europe

The productivity and functioning of mixed-species forests often differs from that of monocultures. However, the magnitude and direction of these differences are difficult to predict because species interactions can be modified by many potentially interacting climatic and edaphic conditions, stand structure and previous management. Process-based forest growth models could potentially be used to disentangle the effects of these factors and thereby improve our understanding of mixed forest functioning while facilitating their design and silvicultural management. However, to date, the predicted mixing effects of forest growth models have not been compared with measured mixing effects. In this study, 26 sites across Europe, each containing a mixture and monocultures of Fagus sylvatica and Pinus sylvestris, were used to calculate mixing effects on growth and yield and compare them with the mixing effects predicted by the forest growth model 3-PGmix. The climate and edaphic conditions, stand structures and ages varied greatly between sites. The model performed well when predicting the stem mass and total mass (and mixing effects on these components), with model efficiency that was usually >0.7. The model efficiency was lower for growth or smaller components such as foliage mass and root mass. The model was also used to predict how mixing effects would change along gradients in precipitation, temperature, potential available soil water, age, thinning intensity and soil fertility. The predicted patterns were consistent with measurements of mixing effects from published studies. The 3-PG model is a widely used management tool for monospecific stands and this study shows that 3-PGmix can be used to examine the dynamics of mixed-species stands and determine how they may need to be managed.

Field-scale electrical resistivity profiling mapping for delineating soil condition in a nitrate vulnerable zone

Venice Lagoon is an extremely heterogeneous environment conditioned by natural changes and anthropogenic pressures. The area is a particularly vulnerable system characterized by high spatial geomorphological variability. Site-specific crop management, defined as the best strategies to manage heterogeneous farmlands, has the potential to maximize agricultural production while preserving soil and water resources. This work was aimed at identifying and characterizing spatial variability within the fields in terms of soil fertility and productive potential using precision agriculture principles. Automatic resistivity profiling (ARP) was implemented to study spatial variability of the field and to define the best localization of twenty soil sampling points. Three years’ historical yield maps were used to determine homogeneous zones within the study area. The application of a fuzzy c-means clustering algorithm led to classification of four homogeneous zones, which were assigned with productive potentials using an ANOVA test of soil features and historical yield data. Such classification was validated by a comparison of the homogeneous zone's productive potential with five-year average production.

FERTILITY AND TOTAL ORGANIC CARBON IN OXISOL UNDER DIFFERENT MANAGEMENT SYSTEMS IN SAVANNAH OF PIAUÍ, BRAZIL

&lt;p&gt;The intensive use of natural resources for food production has ruptured the sustainability of agro-ecosystems. In this context, this study aimed to quantify chemical attributes of Oxisol under five management systems: 1 = conventional tillage (CT); 2 = no-tillage system with millet (NT + M); 3 = crop–livestock integration system with soybean (CL + S); 4 = CL with pasture (CL + P); and 5 = native forest (NF). The following soil depths were studied: 0.00–0.05, 0.05–0.10, and 0.10–0.20 m; and the following traits were quantified: total organic carbon (TOC), soil acidity (pH), soil potential acidity (H + Al) and soil fertility (Ca, Mg, P and K). All treatments modified soil chemical attributes in comparison to NF (p &amp;lt;0.01). The highest phosphorus and potassium levels were observed under CL + S at all evaluated depths. The NT + M treatment increased Ca and Mg levels in layers 0.0–0.05 and 0.10–0.20, whereas CL + S increased base addition (BA), cation exchange capacity (CEC) and base saturation (BS) levels in layer 0.05–0.10 m. Finally, both CL systems improved soil chemical quality, increased surface TOC and carbon stock in depth.&lt;/p&gt;

Influence of long application of fertilizers in crop rotation on the change in the potential and effective soil fertility

The result of 50-years scientific researches, conducted in 10-fields crop rotation on the grey forest dusty light-loamy soil in the northern part of Forest-Steppe at the experimental farm DPDH “Chabany” of National Scientific&#x0D; Centre “Institute of Agriculture of UAAS” are presented in this work. There is stated the importance of potentional soil Fertility forming with saving or increasing of absorbed cation sum, which determines its amelioration processes and provides optimal terms for organic matter and nitrogen compounds transformation. A direct correlation is found between fertilization and labile phosphorus and exchangeable potassium accumulation. The moderate organic-mineral and renewal fertilizing systems are economically and ecologically sensible.

Twelve Years of Stover Removal Increases Soil Erosion Potential without Impacting Yield

Corn (Zea mays L.) stover (non-grain aboveground biomass) in the US Corn Belt is used increasingly for livestock grazing and co-feed and for cellulosic bioenergy production. Continuous stover removal, however, could alter long-term agricultural productivity by affecting soil organic C (SOC) and soil physical properties, indicators of soil fertility and erosion potential. In this study, we showed that 12 consecutive yr of 55% stover removal did not affect mean grain yields at any N fertilizer rate (4.5, 6.3, and 6.0 Mg ha−1 for 60, 120, and 180 kg N ha−1 yr−1, respectively) in a marginally productive, rainfed continuous corn system under no-till (NT). Although SOC increased in the top 30 cm of all soils since 1998 (0.54–0.79 Mg C ha−1 yr−1), stover removal tended to limit SOC gains compared with no removal. Near-surface soils (0–5-cm depth) were more sensitive to stover removal and showed a 41% decrease in particulate organic matter stocks, smaller mean weight diameter of dry soil aggregates, and lower abundance of water-stable soil aggregates compared with soils with no stover removal. Increasing N fertilizer rate mitigated losses in total water-stable aggregates in near-surface soils related to stover removal. Collectively, however, our results indicated soil structure losses in surface soils due to lower C inputs. Despite no effect on crop yields and overall SOC gains with time using NT management, annually removing stover for 12 yr resulted in a higher risk of wind and water erosion at this NT continuous corn site in the western Corn Belt.

Modeling of soil nutrient balances, flows and stocks revealed effects of management on soil fertility in south Ecuadorian smallholder farming systems

Linking nutrient balances and flows to soil nutrient stocks creates a valuable indicator for sustainability assessment in agricultural land-use systems. Therefore, we investigated the impact of management on soil fertility at farm/field scale using the Nutmon approach. A detailed methodology for the adaptation of the difficult-to-quantify flows to the local conditions is described. Research was carried out in the three farming systems of Yantzaza (low-external-input), El Tambo (irrigated cash crops) and San Lucas (integrated nutrient management) in southern Ecuador. For each land-use within a farm (annual and perennial crops, pasture, forest), soil nutrient balances and flows were modeled with Nutmon and soil nutrient stocks were calculated for NPK. Soil nutrient balances were evaluated using potential socio-economic and soil fertility explanatory variables. Balances for the different land-uses in the three research areas varied between −151 to 66 kg ha−1 a−1 for N, −4 to 33 kg ha−1 a−1 for P and −346 to 39 kg ha−1 a−1 for K and were mainly negative. Up to 70 % of the balances’ variability was explained by soil fertility variables and financial flows. Highest external inputs existed in land-uses with a strong market orientation. Land-uses benefiting from a surplus of within-farm flows had the highest soil nutrient stocks. The focus on N fertilization induced highly negative PK balances in annual crops of El Tambo. In contrast, the application of organic fertilizers and nutrient recycling in San Lucas resulted in positive NP balances particularly for perennial crops. NP balances in annual crops of Yantzaza were most negative due to nonexistent fertilization, leaching and burning of crop residues. A non-sustainable land-use of annual crops in Yantzaza was illustrated by total N stock decreases of 4.9 % a−1 and decreased soil organic carbon stocks to 85 % of adjacent forest sites. Results indicated a potential risk regarding sustainable management of soils in the research area and provide a basis for policy and decision makers to develop appropriate management strategies.

Mapping soil organic matter in low-relief areas based on land surface diurnal temperature difference and a vegetation index

Accurate estimates of the spatial variability of soil organic matter (SOM) are necessary to properly evaluate soil fertility and soil carbon sequestration potential. In plains and gently undulating terrains, soil spatial variability is not closely related to relief, and thus digital soil mapping (DSM) methods based on soil–landscape relationships often fail in these areas. Therefore, different predictors are needed for DSM in the plains. Time-series remotely sensed data, including thermal imagery and vegetation indices provide possibilities for mapping SOM in such areas. Two low-relief agricultural areas (Peixian County, 28km×28km and Jiangyan County, 38km×50km) in northwest and middle Jiangsu Province, east China, were chosen as case study areas. Land surface diurnal temperature difference (DTD) extracted from moderate resolution imaging spectroradiometer (MODIS) land surface temperature (LST), and soil-adjusted vegetation index (SAVI) at the peak of growing season calculated from Landsat ETM+ image were used as predictors. Regression kriging (RK) with a mixed linear model fitted by residual maximum likelihood (REML) and residuals interpolated by simple kriging (SK) were used to model and map SOM spatial distribution; ordinary kriging (OK) was used as a baseline comparison. The root mean squared error, mean error and mean absolute error calculated from leave-one-out cross-validation were used to assess prediction accuracy. Results showed that the proposed covariates provided added value to the observations. SAVI aggregated to MODIS resolution was able to identify local highs and lows not apparent from the DTD imagery alone. Despite the apparent similarity of the two areas, the spatial structure of residuals from the linear mixed models were quite different; ranges on the order of 3km in Jiangyan but 16km in Peixian, and accuracy of best models differed by a factor of two (3.3g/kg and 6.3g/kg SOM, respectively). This suggests that time-series remotely sensed data can provide useful auxiliary variable for mapping SOM in low-relief agricultural areas, with three important cautions: (1) image dates must be carefully chosen; (2) vegetation indices should supplement diurnal temperature differences, (3) model structure must be calibrated for each area.

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects

Soil organic carbon (SOC) is a potential soil fertility indicator for regulating nitrogen application in tropical farming systems. However, there are limited studies that have discussed SOC thresholds above or below which crop production could be diminished, or at which no or high response to nitrogen (N) application can be realized. This review explores the drivers of SOC concentration relevant for the establishment of thresholds. We further evaluate existing SOC thresholds for provoking no yield response or significant response to added N fertilizer. Key drivers for SOC concentration relevant in establishing thresholds are mainly climate, topography, texture, and land use management. Soil organic carbon threshold for sustaining soil quality is widely suggested to be about 2% below which deterioration may occur. For added N fertilizer management, specific SOC thresholds seem quite complex and are only valid after assuming other factors are non-limiting. In some soils, SOC levels as low as 0.5% result in fertilizer responses and soils as high as 2% SOC also respond to small N doses. Minimum SOC thresholds can be identified for a given soil type, but maximum thresholds depend on crop N requirements, crop N use efficiency and amount of N applied. However, there seem to exist critical total SOC ranges that could be targeted for optimal indigenous N supply and integrative soil functional benefits. These can be targeted as minimum levels in soil fertility restoration. In all, it is still difficult to establish a single minimum or maximum SOC threshold value that can be universally or regionally accepted.

Dynamics of agricultural use differentially affect soil properties and crop response in East African wetlands

Agricultural land use changes differentially affect soil fertility and crop production potential of wetlands. We studied East African wetlands with contrasting hydro-geological characteristics (high- and lowland floodplains and valley swamps). Land uses ranged from no use and grazing over crop production in flooded and drained fields to abandonment. We classified the dynamics of wetlands’ conversion into agricultural sites and assessed selected soil fertility attributes associated with land use changes, and their effect on the crop production potential in aerobic and anaerobic soils. A conversion of pristine wetlands, differing in soil physical and chemical attributes, into sites of production tended to negatively affect soil total C and N. Effects were stronger with soil drainage and in the coarse-textured soils of the lowland floodplain and the mid-hill valleys. Mineral P application in drained valleys significantly increased available soil P. Crop response followed these patterns with usually higher biomass accumulation and nutrient uptake in flooded than aerobic soils. Wetlands of fine soil texture in the highlands appeared more resilient than coarse-textured soils, particularly when drained. Enhanced crop performance in flooded soils indicates the possibility for partial recovery of the production potential and the rehabilitation of some wetlands.

Land Suitability for Developing Soybean Crops in Bumi Nabung and Rumbia Districts, Central Lampung

Bumi Nabung district consists of 6 villages with a total area of 7,810 ha which are divided into 251 ha of rain fed rice lands, 4,908 ha of dry land, 1,317 ha of lowland, 1,158 ha of yards and 176 ha of others. Rumbia district consists of 14 villages which has a total area of 22,696 ha of land consisting of 2,728 ha of yards, 17,358 ha of dry land, 326 rainfed paddy field, 839 ha of swamp land, 1,470 ha of lowland and 4,232 ha of others. Bumi Nabung and Rumbia districts have a low soil fertility potential that is reflected by the lowof soil pH, CEC, total N, available P, and high level of exchangeable Al and Al saturation. The results assessment based on the physical and chemical characteristics showed that Bumi Nabung district have 5 villages on suitable class S-2 (North Bumi Nabung, East Bumi Nabung, Bumi Nabung Ilir, South Bumi Nabung, and Sri Kencono) and one village New Bumi Nabung has less suitable class S-3. In the Rumbia District, there were 14 villages belonged to suitable class (S-2), namely Reno Basuki, Rekso Binangun, Teluk Dalam Ilir, Rukti Basuki, Restu Baru, Restu Buana, Bina Karya Buana, Bina Karya Putra, Bina Karya Jaya, Bina Karya Utama, Bina Karya Sakti, Joharan, Rantau Jaya Ilir and Rantau Jaya Baru. Bumi Nabung and Rumbia districts have the potential fertility and land suitability for extensification and development of soybean crops. The main technology components to support this program are the use of ameliorant (dolomite and zeolite), the application of organic fertilizers (manure and compost) and inorganic fertilizers (NPK).Keywords: Acid soil, central Lampung, land suitability, soil fertility, soybeans

Stonemeal of amazon soils with sediments from reservoirs: a case study of remineralization of the tucuruí degraded land for agroforest reclamation

This study suggests the employment of accumulated sediments in the reservoir of Tucuruí (Pará /Brazil) to remineralize the surrounding degraded soils. The approach was based on the principles of stonemeal technology. It suggests that the soil can be rejuvenated by crushed rocks rich in macro and micronutrients. Removal of the sediments for agricultural use will bring benefits to family farmers and increase the life cycle of the reservoir and, therefore, energy generation. Geochemical data on retained sediments, soils and rocks in the area of influence of the reservoir were evaluated regarding nutrient transport mechanisms and soil-fertility potential. Results show that sediments from the reservoir contain nutrients levels at least one order of magnitude greater than average Amazon region soils. Our data on soil use and occupation in the region show the degradation areas which could be recovered by stonemeal techniques. Thence, an Agroforestry System was installed, with 12 plots where different mixtures of sediments removed from the reservoir were used, along with crushed rock with or without the addition of NPK and manure. The experiments showed that maximum crop yield and plant growth were attained in the plots where a mixture of sediments, crushed rocks and manure were added.