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Because of the global increase in salt-affected soils, rapid and cost-effective remediations and easily measurable soil salinity evaluations are required. Soil salinity, through EC, and soil sodici...

Chitin, an N-acetyl-D-glucosamine polymer, has been known to enhance plant growth. However, this polysaccharide has not been used extensively in experimental work or agriculture practices because its hydrophobic nature makes it difficult to handle. Chitin nanofiber (CNF), which disperses well in water, can feasibly be used to evaluate the effect of chitin on the promotion of plant growth. In this study, we analysed the contents of inorganic elements and global gene expression to obtain an overview of the growth-promoting action of chitins in plants. Significant increases in the biomass of aerial parts and concentration of chlorophyll following treatment with CNF or short-chain chitin oligomers were observed in tomatoes that were hydroponically cultivated under ultralow nutrient concentrations. The results of the quantification of inorganic elements demonstrated that concentrations of nitrogen and carbon significantly increased in whole tomato plant under chitin treatment. Transcriptome analysis of CNF-treated tomatoes by RNA sequencing showed that the expression levels of genes related to nitrogen acquisition and assimilation, nutrient allocation and photosynthesis were altered. These results indicate that the growth-promoting action of chitin treatment is caused by an improvement in nitrogen uptake efficiency and that CNF could be a useful material for nutrient management in tomato production.

The Kinki, Chugoku, and Shikoku regions are located in the west-central part of Japan. The major soil great groups distributed in these regions are Brown Forest soils (47.6%), Red-Yellow soils (16.0%), and Fluvic soils (14.2%) with very limited distribution of Andosols (8.6%), reflecting mountainous geography. Those used for agricultural land are dominated by Fluvic soils (65.5%) followed by Brown Forest soils (14.2%) and Red-Yellow soils (7.8%), reflecting high ratio of paddy (72.8%) in agricultural fields. In these regions, diverse types of agriculture are conducted corresponding to a variety of soil types with various geographical and climatic circumstances, including paddy rice production as well as the production of vegetables (e.g., traditional vegetables), fruits (e.g., orange in Wakayama and Ehime Prefectures and Japanese apricot (Ume) in Wakayama Prefecture), and tea in upland fields. Among them “Minabe-Tanabe Ume system” and “Nishiawa slope farming system” are designated as globally important agricultural heritage systems (GIAHS) in these regions. Environmentally friendly agriculture has been carried out, which is defined as sustainable agriculture in which crop productivity is well balanced with environmental quality by recycling materials and reducing the input of chemical fertilizer and pesticides. A wide variety of countermeasures has been also accomplished to reduce greenhouse gas emissions and leaching of nitrate, and harmful chemical substances are also discussed.

We evaluated phytoremediation potential of a calcareous saline-sodic soil with Prosopis glandulosa relying on either N2 fixation (NFIX) or inorganic N (IN) and gypsum. Straw and root dry matter of NFIX were 60% and 67% higher than that of IN, respectively. While both plants relying on IN or NFIX retained nearly similar Ca2+, Na+ level in IN lysimeters was 1.8 folds that of NFIX, whereas levels of Na+ and K+ in roots of NFIX were 13% and 24% higher than that of IN plants. P. glandulosa relying on NFIX and IN released 39% and 50% Na+ of that released by the gypsum. P. glandulosa produced more than the gypsum treatment and induced 24% of Ca2+ solubilization found in the gypsum treatment. Translocation factor of Na+ and the K+/Na+ ratio in NFIX and IN were 0.58, 0.99 and 13.2, 7.0, respectively. The practical implication of this study conclude that P. glandulosa grown with NFIX or IN is an alternative practice for amelioration of calcareous salt-affected soils.

Degradation by wind erosion is detrimental to both soil and land quality in arid regions. This study was conducted to investigate the effectiveness of some organic amendment - poultry manure (PM), farmyard manure (FYM) and rice husk (RH) and were applied on the sandy soil surface at 1 and 3 cm thickness and control (no treatment; C) to make clear the sand particles stabilization. Total soil nitrogen, organic carbon (OC), and pH in the PM and FYM treatments exceeded those in the RH treatment. Soil hardness in the PM compost was 6.7, 1.4, and 2.7 times the mean determined in the control, FYM and RH, respectively, whereas CaCO3 in the PM treatment was 56 and 69% higher than the levels in FYM and RH, respectively. Soil hardness varied in the order of PM 3 cm > PM 1 cm > FYM 1 cm > FYM 3 cm > RH 1 cm > RH 3 cm > C. The erodible fraction (0.85–1.0 mm) decreased linearly with increase in soil hardness (R2 > 0.9), OC, CaCO3. Farmyard manure and PM composts decreased the erodible fractions by up to 5 and 15%, respectively. Surface application of PM compost is an effectively stabilized the sand particles during this study.

The present study examined the effect of excessive application of farmyard manure (FM) on rice production and environmental pollution in paddy fields of Japan. A long-term field experiment was conducted during the period 1976–2006 to examine the trends of rice yield and yield components as affected by the excessive FM application (20 Mg ha−1 year−1 containing 110 kg N, 180 kg P2O5, and 320 kg K2O). Rice growth, soil fertility, and surface water quality were also assessed in the final year (2006). The results obtained were compared with those of a conventional practice with recommended doses of inorganic fertilizer (IF), i.e. 85 kg N, 68 kg P2O5, and 53 kg K2O ha−1 year−1, and an unfertilized control (CR). The excessive FM application resulted in a gradual decrease in grain yield, which was mostly explained by the reduction of grain fertility under the luxuriant rice growth. This reduction may have been due to the higher accumulation of soil nutrients such as N, P, and K. Moreover, the excessive FM...

A greenhouse experiment was conducted to study the effects of saline water irrigation and soil salinity on the growth of kochia (Kochia scoparia (L.) Schrad.) and alfalfa (Medicago sativa L.). The alfalfa production was low, and half of the plants withered and died under soil electrical conductivity of ≥4 dS m−1. However, high salinity did not affect kochia growth. The mechanism of sodium absorption differs between kochia and alfalfa. Kochia has a salt-tolerance mechanism whereby the sodium concentration in the plant does not increase, regardless of the environmental conditions of the soil. However, the sodium concentration in alfalfa increases with increasing concentrations of sodium in the soil. Accordingly, changes were observed in the salt composition of alfalfa that harmed the plant. Although good kochia growth was observed in soil with limited water irrigation, it is difficult to grow alfalfa using the same quantity and salinity of irrigation water as used for kochia. Kochia can be cultivated using limited water and in highly saline soil in arid and semiarid regions. Furthermore, since kochia cultivation requires limited irrigation water, the plant may suppress the increase in the salinity of the soil and irrigation water. Therefore, in saline soil in arid and semiarid regions, kochia may be promising as an effective forage crop substitute for alfalfa.

The salt-sensitive humid tropical biodiesel crop, Jatropha curcas, was subjected to a 28-day exposure to salinity (0, 50, 100, and 200 mM NaCl), and activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX), the rate of lipid peroxidation, stomatal conductance, mineral contents, and chlorophyll (Chl) content were compared to corresponding characteristics of J. cinerea, a related wild species of saline-dry areas. Biomass production decreased under the influence of 50 mM NaCl in both species, and the reduction was larger in J. curcas than in J. cinerea at the higher NaCl concentrations. In both species, stomatal conductance and transpiration decreased, leaf temperature and Na+ concentration increased under salt treatment; salinity effect was stronger in J. curcas. Chl degradation was enhanced only in J. curcas. In both Jatropha species, SOD, CAT, and POX activities increased with salinity. J. curcas showed the higher antioxidant activity than J. cinerea. Lipid peroxidation was observed only in J. curcas at concentrations above 100 mM NaCl, partially due to a greater reduction in stomatal conductance and/or the poor ROS-scavenging system. Thus, J. cinerea had more favorable characteristics to adapt to saline environments, and young J. curcas plants could adapt to salt-affected land if soil salinity was moderate (about 50 mM NaCl in solution).

Irrigation with wastewater supports agricultural production and the livelihoods of millions of smallholder farmers in many parts of the world. Considering the importance of better wastewater management at the local and national levels, there is a need for updated national data on wastewater generation, treatment, and use, which would also assist in regional and global wastewater assessments. While searching data and literature in published or electronic forms for 181 countries, we find that only 55 countries have data available on all three aspects of wastewater – generation, treatment, and use. The number of countries with one or two aspects of wastewater generation, treatment, and use is 69, while there is no information available from 57 countries. Of the available information, only 37% of the data could be categorized as recent (reported during 2008–2012). The available data suggest that high-income countries on average treat 70% of the generated wastewater, followed by upper-middle-income countries (38%), lower-middle-income countries (28%), and low-income countries, where only 8% of the wastewater generated is treated. The availability of current information on wastewater generation, treatment, and use is crucially important for policy makers, researchers, and practitioners, as well as public institutions, to develop national and local action plans aiming at safe and productive use of wastewater in agriculture, aquaculture, and agroforestry systems. The country level information aggregated at the regional and global levels would help in identifying the gaps in pertinent data availability and assessing the potential of wastewater in food, feed, and fish production at different scales.

The physicochemical properties of soil profiles in the Luohui Irrigation Scheme located along the southeastern edge of the Loess Plateau in China were investigated. The scheme covers part of a river terrace system along the Luohe River. The study area was approximately 31 × 16 km with a north–south gradient and a difference in altitude of about 40 m. The terrace system was divided into a high terrace (HT; 371–389 m), an intermediate terrace (IT; 360–370 m), and a low terrace (LT; 344–359 m). The HT and LT soils showed different trends in salt accumulation in their surface horizons and overall soil profiles. Surface soils and soil profiles on the HT contained a greater amount of clay and silt than those on the LT, which had coarser soil textures. The IT had soils with characteristics intermediate between those of the HT and LT. A negative relationship was found between soil pH and soil electrical conductivity, and positive ones between soil electrical conductivity and silt contents and between water electr...

The use of organic manures as an alternative to chemical fertilizers is an option for the development of sustainable farming systems in Japan. The present study examined the effect of rapeseed oilcake (RO) not only on yield and yield components of rice (Oryza sativa L.) but also on soil fertility parameters and surface water quality in a paddy field by comparing them with the effects of conventional inorganic fertilizer (IF) and a control (CR), that is, natural (unfertilized) system. The long-term field experiment from 1990 to 2006 demonstrated the indigenous sustainability of paddy systems, because husked grain yield and shoot biomass in the CR plot remained at moderate levels (ave. 323 ± 56 g m−2 and 843 ± 166 g m−2, respectively) over 17 successive years. Meanwhile, the application of RO comparatively improved grain yield (ave. 538 ± 83 g m−2) and shoot biomass (ave. 1478 ± 187 g m−2) to almost the same level as with IF (ave. 538 ± 68 g m−2 and 1511 ± 173 g m−2, respectively) during the study period. S...

The present study aimed to investigate the effects of K-type and Ca-type artificial zeolites on the growth and water and element absorptions of kidney bean (Phaseolus vulgaris L.), tomato (Lycopersicon esculentum Mill), maize (Zea mays L.) and beet (Beta vulgaris L.) in high sodic soil. Tottori sand dune soil, which was used as a control, was converted to high sodic soil mixed with salts. Each type of zeolite was mixed into the high sodic soil at rates of 0, 1, 2 and 5%. The results showed that kidney bean, tomato and maize died in high sodic soil 25–27 days after transplanting (DAT), whereas beet survived, although its growth was extremely suppressed at 26 DAT. The addition of Ca-type zeolite improved growth in all of the tested plants. Even 4 DAT the growth of beet was improved by recovery of water absorption, and growth of tomato was improved by recovery of Ca and K absorptions and cation balance, and restriction of Na absorption. Growth of kidney bean and maize improved at 11 or 13 DAT by rec...

The present study investigated macro- and micronutrient status in the soils under the native forest (NF), cropland (CL) and rangeland over 27 years in Colonia Okinawa, Santa Cruz, Bolivia, in order to assess the effect of land use on soil fertility in the region. The C, N and P pools in the soil of CL were less by 60, 57 and 27% as compared to NF, respectively. The rangeland with Panicum maximum (RG) showed almost similar values of C, N and P pools to CL, while the values in the rangeland with Paspalum notatum (RB) were relatively closer to NF. Mehlich-3 extractable P, Ca and Mg considerably declined in CL, RG and RB, but an inverse trend was observed in Mehlich-3 extractable K probably due to the stimulation of weathering of illite in the soil. Mehlich-3 extractable Mn, Fe and Cu were tended to increase in RG and RB, which suggested possible accumulation of these metals because of the manure deposited by grazing cattle on the rangelands. Besides C, N and P pools, the values of Mehlich-3 extractable K, Mn, Fe and Zn were less in RG than RB because of greater exploitation of these nutrients in RG than RB. There was a significant correlation between C, N, P, Ca, Mg and Zn suggesting that the dynamics of these components could be associated with the organic matter in the soil. The findings of this study clarified the soil chemical degradation in the cropland and rangeland. However, the magnitude of the land chemical deterioration under the rangeland was highly variable depending on the grass species.

Composting of livestock manure is a viable and environmentally sound method of waste management. It is usually an aerobic process, but anaerobic composting through use of digesters is also a widely practiced waste management option, due to its cost efficiency. Although physicochemical changes during composting have been documented, information on the behavior of total and available heavy metals during composting of livestock manure is scanty. Such information is necessary for an efficient compost use and environmental management practice. In the present investigation, we compared the behavior of total and available heavy metals in a mixed cattle + swine + chicken manure which was composted for 195 days, with and without air, using rice straw as a bulking agent. Marked increases in total Fe, Zn, Cu and Mn, especially under anaerobic conditions were noted during composting. Conversely, aerobic composting significantly decreased available Fe by 36%, Zn by 50%. Cuby 14% and Mn by 27% at 195 days. The...

The behavior of humic substances (HS) and phosphorus (P) fractions in livestock manure co-composted with rice straw was studied by chemical and spectroscopic analyses. Composting was accompanied by a decrease in the levels of carbon (C) and nitrogen (N) as well as HS and fulvic acid (FA) fractions. The elemental content (weight %) of humic acid (HA) extracted from the compost showed a high C content and low oxygen (O) content, possibly due to a low degree of oxidation. The N/C and H/C ratios of HA decreased as the compost matured, whereas the O/H and O/C increased. The decline in the H/C ratio from 1.24 at 0d to 1.0 at 195d indicated an increase in the aromatic structure of the HA. The absorbance curve for the HS showed a decrease in the slope with time, up to 42d. The optical density of HS increased with time of composting with a peak at 42d. Also the Δ log K values of FA increased appreciably with time of composting whereas those of HS and HA were little changed. Water-soluble and HCl-soluble-P were the...

One of the options for achieving an adequate food supply in tropical Africa is by bringing more land into production. This often requires clearing and developing new vegetation areas for agricultural production. In sub-Saharan Africa, large areas of forest are being cleared for cultivation without adequate knowledge as to the consequences of the clearing method employed. This study was therefore initiated to, among other objectives, assess the effects of some forest clearing methods on soil compaction, texture, and micronutrients. Treatments were the following five clearing methods: (1) mechanical (MC), (2) semi-mechanical (SMC), (3) slash and burn (manual) (SB), (4) mechanical – no planting (MCNP), and (5) slash and burn – no planting (SBNP). After clearing, we planted maize and cowpea in every other row during the first year, and planted maize and cassava during the second year in the plots of treatments 1–3. Changes in soil texture, bulk density, and exchangeable Fe, Zn, Mn, and Cu were determi...

Studies into cation release in manured soils are very limited and poorly documented. The present investigation was therefore aimed at comparing the influence of manure application on cation [calcium (Ca), magnesium (Mg) and potassium (K)] mineralization in four different soils. Four sources of livestock manure: chicken manure (PM), cattle manure (CM), swine manure (SM), ostrich manure (OM) and a control (no manure) were added to the soils (Andosol, red–yellow soil, masa soil, and sandune soil) and incubated for 8 weeks at room temperature. Soils were sampled at weekly intervals and analyzed for pH, EC, and exchangeable Ca, Mg, and K. Soil pH increases ranging between 5.8 in CM and 6.6 in OM treatments were observed. Chicken manure increased EC from the mean initial level of 4.4 to 11.8 mS/m. Cumulative mineralized Ca and Mg was highest in red–yellow soil followed by masa soil. The lowest values for Ca (1.8 cmolc kg−1) and Mg (1.3 cmolc kg−1) were in Andosol.

Soybean (Glycine max L., Merr.) is considered to have relatively high level of reproductive abscission, but research information on how fertilizer use influences this problem is scanty. Field trials were therefore carried out for two seasons (1996 and 1998) to investigate the abscission levels of three soybean cultivars (TGX 536‐02D, TGM 579, and Samsoy 11) as affected by foliar application of urea during the early reproductive stages. Flowering was not significantly increased by urea application, although all fertilized plants had fewer flower abortions than control. Fertilizing twice at full‐flowering and pod‐setting (R2–R3) or thrice at first‐flowering, full‐flowering, and pod setting (R1–R2–R3) stages gave the least flower abortion. In TGX 536‐02D the average flower abortion was 61% in 1996 and 57% in 1998. The abortion rate was about 60% for TGM 579 in 1996 and Samsoy 11 in 1998, respectively. Percentage pod abortion was generally reduced especially at the R1–R2–R3 stage, while the proportio...

Beets were grown on soils with various exchangeable sodium percentages (ESP). A saline non-sodic soil (SA, ESP = 3.2), a saline sodic soil (SO, ESP = 23), and a saline high sodic soil (HSO, ESP = 78) were prepared from Tottori sand dune soil (CO). K-type and Ca-type artificial zeolites (50 g kg−1) were applied to these soils in order to evaluate their effects on the chemical properties of saturation extracts of the soils, water deficit, cation uptake and transport, and cation balance of beet plants. In the zeolite-free treatments, beet growth was accelerated in SA and SO, but was suppressed in HSO compared with CO. The addition of both types of zeolites ameliorated plant growth in all the soils studied, especially HSO. The relative dry weight of the soils treated by the K-type zeolite to the zeolitefree soil was 189% for CO, 125% for SA, 130% for SO, and 222% for HSO. For the soils treated with the Ca-type zeolite, the values were 169, 116, 132, and 341%, respectively. In SA, SO, and HSO, the add...

Knowledge of exchangeable cation chemistry can provide clues about tendencies toward either soil dispersion or flocculation as exchangeable sodium accumulates. The accumulation of sodium might be influenced by soil texture and degree of salinity. The effects of clay minerals, composition, and salini

Salinity and soil nutrient deficiencies are the main factors reducing plant productivity in arid and semiarid areas. Among the essential elements, nitrogen is usually the most growth limiting plant nutrient in saline or non-saline soils. A pot experiment was carried out in the greenhouse to evaluate the influence of composted manure and urea as nitrogen sources on growth and mineral [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na)] content of maize (Zea mays L.) under different levels of salinity. Saline soils were prepared from an infertile loamy-sand soil, namely masatsuchi, by adding a mixture of Ca, Mg, and Na salt solutions with concentrations of 60, 110, and 160 mmolc L−1. The final salinity levels (ECe) achieved were 4, 9, and 13 dSm−1 denoted as S1, S2, S3, respectively; S0 denotes untreated soil. The pH of the saline soils ranged from 7.1 to 7.4. Nitrogen was applied at four levels as follows: urea, composted manure, ½ urea + ½ composted manure, and a co...

The adverse effects of forest clearing on crop yield have often been directly ascribed to decline in soil fertility. However, the effect of various forest clearing methods on crop nutrient uptake as reflected by the content in the leaf tissues has been the subject of few scientific investigations. A study to determine the effect of forest clearing on nutrient content of some arable crops was, therefore, carried out in the tropical rainforest of south-western Nigeria. Three forest clearing methods—mechanical, semi-mechanical and manual clearing—were used, while maize, cowpea, and cassava were the test crops. Nutrient content in the tissues of these crops was assessed by sampling maize ear leaves at silking, youngest mature leaves (YML) of cowpea at flowering and YML of 3-month-old cassava for analysis. Correlation analysis was carried out to establish the relationship between nutrient content and crop yield. The method of forest clearing had no significant effect on the nutrient content of maize and cowpea during the first cropping cycle. However, nutrient content of maize in the manually cleared plots was higher than those in the semi- and mechanically cleared plots for all elements analyzed except Mg. Nitrogen content of cowpea was much higher than that of maize. Except for P and K, the nutrient content of cassava was not markedly different among the forest clearing methods. Calcium and P content in the leaves of maize and cassava varied inversely with their levels in the soil, implying that crop uptake could have accounted for the differences in their availability within the soil. Nitrogen, P and K had significant positive correlations with maize yield (r = 0.77, 0.89, and 0.71). Potassium content also had significant positive correlation with cassava root yield (r = 0.69). This is not surprising because compared with other crops, cassava requires large amounts of K for starch formation and root development. It is concluded that differences observed in crop yields under different forest clearing methods are a function of nutrient uptake and availability within the soil. However, the uptake of some nutrients does not seem to be determined by the level of soil availability alone.

This study sought to evaluate the efficacy of aerobic and anaerobic composting of inoculated banana peels, and assess the agronomic value of banana peel-based compost. Changes in the chemical composition under aerobic and anaerobic conditions were examined for four formulations of banana peel-based wastes over a period of 12 weeks. The formulations i.e. plain banana peel (B), and a mixture with either cow dung (BC), poultry litter (BP) or earthworm (BE) were separately composted under aerobic and anaerobic conditions under laboratory conditions. Inoculation with either cow dung or poultry litter significantly facilitated mineralization in the order: BP>BC>B. The rate of decomposition was significantly faster under aerobic than in anaerobic composting conditions. The final composts contained high K (>100 g kg(-1)) and TN (>2%), indicating high potential as a source of K and N fertilizer.

Selected farmlands in southern Baja California, Mexico, were surveyed to determine the levels and the causes of salinization/sodication in irrigated agricultural soil. The salt dynamics observed in profiles differed from farm to farm. Low EC and high pH levels were observed in the profiles of sandy fields, because the salt composition of these soils can easily change when salts are leached by irrigation water that contains carbonates of sodium. On the other hand, high levels of salinity and sodicity were observed in the soils of clayey fields. Soil salinization/sodication is complexly interrelated with soil characteristics, the amount and composition of salts in the soil, the quantity and quality of irrigation water applied, and the irrigation methods used. Our findings indicate that irrigation water in Baja California should be supplied at a rate that is sufficient to meet crop requirements without exacerbating salt accumulation.