Changes In Soil Nutrient Status Research Articles

Effect of Organic Manures and Phosphorus on Soil Nutrient Status in Kharif Rice

Field experiments were conducted at Agricultural College Farm, Bapatla during Kharif and Rabi seasons of 2017-2018 and 2018-2019 to study the Phosphorus dynamics in relation to nutrient management in rice- blackgram cropping sequence with respect to changes in soil nutrient status. Results of two years (2017-2019) experimentation revealed that at all growth stages of rice, significantly highest available nitrogen, phosphorus and potassium in soil were recorded with application of RDNK+Dhaincha @ 10t ha-1 (M3) and this was on par with RDNK+ Sunhemp @ 10t ha-1(M2), whereas lowest was recorded in RDNK (M0) alone in both seasons of study. Among the P levels the available nutrient status (N, P and K) were increased with the increasing level of P from 0 (P1) to 120 kg P2O5 (P5) ha-1, irrespective of the nutrients imposed to rice crop. Significantly highest was recorded in P5 (120 kg P2O5 ha-1) and this was on par with P4 (90 kg P2O5 ha-1), whereas the lowest was recorded in treatment P1 that received 0 kg P2O5 ha-1.

Fertilization effects on soil microbial composition and nutrient availability in integrated rice-livestock production systems

Integrated crop-livestock systems (ICLS) in paddies are an important strategy to reduce fertilizer requirements of rice (Oryza sativa). Legume crop rotations and fertilization increase soil carbon (C) and nitrogen (N) availability compared to rice monocropping. Our objectives were to evaluate the effects of fertilization, namely P and K, in no-till ICLS of continuously flooded rice and rice-soybean rotation in subtropical paddy fields on: (i) soil microbial community, (ii) labile C and N pools, (iii) microbial groups, and (iv) rice yield. Both ICLS were annual ryegrass pastures under beef cattle grazing during the winter season without tillage. Although flooded rice yield did not respond to P and K fertilization in either ICLS, P and K fertilization increased microbial biomass C and N content, and permanganate-oxidizable C (POxC) by 37%, 36%, and 42%, respectively, in both production systems, due to alleviation of nutrient limitation for microbial growth. ICLS under soybean-rice rotation had higher C availability and 22.4% higher rice yield than the rice monocropping. Positive relationships were observed between microbial biomass N and Gram-positive (G+; R2 = 0.61), Gram-negative (G-; R2 = 0.54) bacteria, and saprophytic fungi (R2 = 0.45). However, total fungi was almost 10 times lower than the PLFA of total bacteria on average of cropping systems. G+ bacteria were the only microbial group correlated with N availability under flooded rice. We conclude that P and K fertilization has a direct impact on the microbial community and biomass and consequently on the C and N availability, but does not increase rice yield under no-till ICLS. Soybean-rice rotation yields more than rice monocropping system under ICLS and soil bacteria are more sensitive than saprophytic fungi to changes in soil nutrient status during flooding period in paddy fields.

The Admont Grassland Experiment: 70 years of fertilizer application and its effects on soil and vegetation properties in an alluvial meadow managed under a three-cut regime

Fertilizer application is a widely used management technique for increasing forage production from agricultural grassland. Fertilization is also a key driver of changes in soil nutrient status and plant species composition of grassland as shown in many short-term studies. Results from long-term experiments can further improve understanding of plant-soil relationships and help with management recommendations for agricultural and environmental outcomes. We collected data from a long-term experiment on alluvial meadow (Admont Grassland Experiment, Austria; established 1946) with 24 fertilization treatments managed under a three-cut regime. Soil sampling in autumn 2015 and vegetation sampling in spring 2016 were conducted in seven selected treatments. Combinations of N (nitrogen 80 kg ha−1), P (phosphorus 35 kg ha−1) and K (potassium 100 kg ha−1) were applied annually and compared with a non-fertilized control. Treatments were: Control, N, P, K, NP, NK, PK and NPK fertilization.Long-term different fertilization affected soil pH and nutrient concentrations in the soil and plant species composition, but no significant effects on species richness were found. Short species (<0.5 m height) prevailed in all treatments regardless of nutrient application, probably as a result of the three-cut defoliation. The dry matter biomass (DMB) yield in the Control was limited by N and P and synergisticly co-limited by N, P and K, and DMB yields of more than 5 t ha−1 per year were achieved under nutrient combinations containing P (NP, PK, NPK) without loss of species richness.Results from the Admont Grassland Experiment show that the tested nutrient combinations significantly increased DMB yield and changed the species composition, but without significant effects on species richness. Long-term biomass yields of more than 5 t ha−1 DMB per year can be achieved with any nutrient combination containing P without loss species richness in an alluvial meadow managed under a three-cut regime.

Changes in soil chemical properties in agroforestry system at USU Arboretum Kwala Bekala

One of the opportunities for utilization and optimization of the Arboretum land is by intensive cultivation of crops commodities to fulfil the needs of food, vegetables and other commodities. This study aims to analyse changes in soil nutrient status in four types of forest trees combined with agroforestry using soybean. Soil survey was carried out in area of USU Arboretum Kwala Bekala by soil sampling and then analyzed in the laboratory. Composite soil samples were taken from Jabon tree stands, (Anthocephalus cadamba Miq.), Gmelina (Gmelina arborea Roxb.), Rubber (Hevea brasiliensis.), and Mindi (Melia azedarach L.) at a depth of 0-30 cm. This sampling was carried out twice, namely before planting and after harvesting of soybeans. The results of soil analysis were assessed based on the criteria of Soil Research Center. Parameters observed for soil sample were N total (Kjeldahl method), phosphate (Bray method), C organic (Walkey and Black), Potassium and Sodium (Flame photometer), Calcium and Magnesium (AAS). The data obtained were analysed using a paired t test at the level of α 0.05. Almost all of the values of soil chemical properties gradually increased, and significant differences in those chemical properties were found between two condition, before and after the growing of soybean in four type stand of woods. Generally, Agroforestry system in four main stands (Rubber, Gmelina, Mindi and Jabon) with soybean for period 1-year can improve soil chemical fertility through increasing pH, C organic, N total, P available, Potassium, Na and Ca.

Effect of Sterilization on Arbuscular Mycorrhizal Fungal Activity and Soil Nutrient Status

The purposes of this study are to evaluate the effect of sterilization on arbuscular mycorrhizal fungal activity and soil nutrient status, and to determine the time needed to eliminate the colonization capability of existing AM fungi, minimize changes in soil nutrient status, and save time and energy needed to create sterile soil samples for AM inoculation. The effects of autoclaving (121 °C, 0.1 Mpa) and heating (180 °C) for 0.5, 1, 2, or 4 h on colonization capability, germination, and viability of the AM fungus Rhizophagus irregularis were investigated. The effects of both sterilization methods on pH and on concentrations of ammonium, nitrate, phosphate, potassium, and organic matter in soil samples 0.1 m thick were compared. For sterilization of longer than 1 h, both autoclaving and heating reduced colonization to less than 0.1% and depressed germination rates and the viability of arbuscular mycorrhizal fungi spores, but increased concentrations of soil macronutrients. Autoclaving for 0.5 h was sufficient to eliminate arbuscular mycorrhizal fungal colonization but heating required at least 1 h. Within 1 h, the influence of both autoclaving and heating on soil nutrient status was limited and acceptable. For the most effective investment of time and energy, arbuscular mycorrhizal-free soil 0.1 m thick can be generated with 0.5 to 1 h of autoclaving (121 °C, 0.1 MPa) or 1 h of heating (180 °C).

Study of changes in soil chemical properties of Asma village of Valsad district

A study was carried out to examine the changes in soil chemical properties and crop yields in a area of Asma village of Valsad district (Gujarat). The result showed that the mean values of soil pH and EC were increased with time. Although, average values of organic carbon, available P and available K were decreased year by year. Also difference between maximum and minimum values of soil pH, EC, organic carbon, available P and available K become larger with time due to greatly different in fertilizer application between farmers. Though the yields of crops were increased with cultivation of hybrid varieties but the changes in soil nutrient status have shown there might be need to improve soil management with application of organic and biofertilisers to sustain the fertility of the soil.

Influence of scattered Acacia trees on soil nutrient levels in arid Tunisia

Scattered trees often function as fertile islands in harsh environments such as arid and semiarid lands. To understand their impact on the soil nutrient status, an in-depth study accounting for spatial patterns in nutrient levels was conducted in an Acacia raddiana forest-steppe ecosystem in arid Tunisia. Changes in soil organic matter and total N, extractable P and exchangeable K+ were examined considering a distance gradient in both horizontal and vertical direction. In addition, the effect of tree age was incorporated to determine temporal changes in soil nutrient status after reforestation. Higher organic matter and nutrient levels in the upper soil layer (0–10 cm) were found up to 175% of the canopy radius, especially for trees older than 75 years. Organic matter and nutrient concentrations below canopy were significantly higher up to a depth of 20 cm. Increased levels of organic matter and total N with increasing tree age were found below canopy reaching a maximum after 75 years. Spatial patterns in soil chemical properties exist from underneath to outside the canopy and with increasing depth. When combined with tree age, the impact of scattered A. raddiana trees on spatio-temporal changes in resource availability can be studied on a field scale.

Growth, yield, and calcium and boron uptake of tomato(Lycopersicon esculentum L.) and cucumber (Cucumis sativus L.) asaffected by calcium and boron humate application in greenhouse conditions

The objective of this study was to examine the effect of calcium humate, boron humate, and humic acid solutions on growth, yield, quality, and calcium and boron uptake of tomato (Lycopersicon esculentum L.) and cucumber (Cucumis sativus L.), as well as changes in soil nutrient status after crop harvest. Four different concentrations (500, 1000, 3000, and 5000 mg kg-1) of calcium humate (12% CaO, 15% humic and fulvic acid), boron humate (10% BOH4, 15% humic and fulvic acid), and humic acid (15% humic and fulvic acid) were used in this research. The results revealed that Ca humate, B humate, and humic acid treatments applied at different rates positively affected the total marketable yield, average fruit weight, fruit diameter, fruit length, and leaf dry matter of tomato and cucumber plants. However, no statistically significant differences were observed among the treatments in terms of total soluble solids, fruit dry matter, chlorophyll, and plant length. The highest tomato yield (159,682 kg ha-1) was obtained from 2936 mg kg-1 Ca humate application, while the highest cucumber yield (172,992 kg ha-1) was obtained from 2910 mg kg-1 Ca humate application. In addition, the macro- and micronutrient concentration in leaves and fruits also increased significantly with these applications. Translocations of Ca and B from leaf to fruit were also affected positively by the Ca and B humate applications. Leaf Ca/fruit Ca ratio in tomato and cucumber decreased from 20.55 to 2.42 and from 10.70 to 1.37, respectively, while leaf B/fruit B ratio decreased from 15.80 to 1.82 in tomato and from 14.31 to 2.64 in cucumber. The applications also upgraded soil health by modifying the chemical characteristics of the soil and enhancing its nutrient status. The results showed that Ca and B humate nutrient sources should be used as an economical and simple application for tomato and cucumber plants without Ca and B deficiency during the plant growth period.

Wood ash in boreal, low-productive pine stands on upland and peatland sites: Long-term effects on stand growth and soil properties

The effect of wood ash on growth of Scots pine was studied in 64- to 75-year-old stands on three upland sites (Exps. 402, 407 and 408) for 20years and in a 30-year-old Scots pine stand on an oligotrophic peatland site (Exp. 251) for 25years. In Experiments 407 and 251 the responses of soil chemical properties and soil microbiological processes related to C and N cycling were also studied. The upland experiments included a control and a treatment with 3Mgha−1 of wood ash. In Exp. 407, 120kg Nha−1 was applied together with ash; this experiment also included a treatment with N alone. The peatland experiment included a control and a treatment with 4.8Mgha−1 of wood ash. All experiments had 3 replications. Wood ash significantly decreased soil acidity on all sites. On the upland site, after 20years, the concentration of K2SO4-extractable DOC and the rates of C mineralization (CO2–C production) and net N mineralization were all higher in the Ash+N treatment than in the control or N treatments. However, the treatments did not significantly affect the amounts of C or N in the microbial biomass or the concentration of NH4–N. On the peatland site, after 27years, ash stimulated C mineralization and cellulose decomposition, but microbial biomass C or N, net N mineralization or the concentration of N were not affected significantly. On both the upland and peatland site, net nitrification was very low in all treatments. In Exp. 408, the volume growth in the control and Ash treatment was during the 20-year study period 60 and 64 m3ha−1, respectively, and in Exp. 402 108 and 120m3ha−1, respectively, the latter difference being significant. In Exp. 407, the volume growth in the Ash+N treatment was during the 20-year study period significantly higher (92m3ha−1) than in the N and control treatments (76 and 73m3ha−1, respectively). On the peatland site during the 25-year study period the growth was 145 and 169m3ha−1, in the control and Ash treatments, respectively. In conclusion, the long-term positive response of stem growth to wood ash on peatlands and N fertilized upland sites can be partly explained by changes in soil nutrient status and by microbial processes related to C and N cycling.

The seasonal pattern of soil microbial community structure in mesic low arctic tundra

Soil microorganisms are critical to carbon and nutrient fluxes in terrestrial ecosystems. Understanding the annual pattern of soil microbial community structure and how it corresponds to soil nutrient availability and plant production is a fundamental first step towards being able to predict impacts of environmental change on ecosystem functioning. We investigated the composition, structure and nutrient stoichiometry of the soil microbial community in mesic arctic tundra on 9 sample dates in 6 months from winter to fall using phospholipid fatty acid analysis (PLFA), quantitative polymerase chain reaction (qPCR), epifluorescent microscopy and chloroform-fumigation–extraction (CFE). PLFA analysis indicates that the winter microbial community was fungal-dominated, cold-adapted and associated with high C, N and P in the soil solution and microbial biomass. The microscopy data suggest that both bacteria and fungi were active and growing in soils between −5 °C and 0 °C. A significant shift occurred in the PLFA data, qPCR patterns, microscopy and microbial biogeochemistry after the thaw period, resulting in a distinct community that persisted through our spring, summer and fall sample dates, despite large changes in plant productivity. This shift was characterised by increasing relative abundances of certain bacteria (especially Gram +ves) as well as a decline in fungal biomass, and corresponded with decreasing C, N and P in the soil solution. The summer period of low substrate availability (plant–microbe competition) was associated with microbial indicators of nutritional stress. Overall, our results indicate that tundra microbial communities are clearly differentiated according to the changes in soil nutrient status and environmental conditions that occur between winter and post-thaw, and that those changes reflect functionally important adaptations to those conditions.

Production and carbon allocation in monocultures and mixed-species plantations of Eucalyptus grandis and Acacia mangium in Brazil

Introducing nitrogen-fixing tree species in fast-growing eucalypt plantations has the potential to improve soil nitrogen availability compared with eucalypt monocultures. Whether or not the changes in soil nutrient status and stand structure will lead to mixtures that out-yield monocultures depends on the balance between positive interactions and the negative effects of interspecific competition, and on their effect on carbon (C) uptake and partitioning. We used a C budget approach to quantify growth, C uptake and C partitioning in monocultures of Eucalyptus grandis (W. Hill ex Maiden) and Acacia mangium (Willd.) (treatments E100 and A100, respectively), and in a mixture at the same stocking density with the two species at a proportion of 1 : 1 (treatment MS). Allometric relationships established over the whole rotation, and measurements of soil CO(2) efflux and aboveground litterfall for ages 4-6 years after planting were used to estimate aboveground net primary production (ANPP), total belowground carbon flux (TBCF) and gross primary production (GPP). We tested the hypotheses that (i) species differences for wood production between E. grandis and A. mangium monocultures were partly explained by different C partitioning strategies, and (ii) the observed lower wood production in the mixture compared with eucalypt monoculture was mostly explained by a lower partitioning aboveground. At the end of the rotation, total aboveground biomass was lowest in A100 (10.5 kg DM m(-2)), intermediate in MS (12.2 kg DM m(-2)) and highest in E100 (13.9 kg DM m(-2)). The results did not support our first hypothesis of contrasting C partitioning strategies between E. grandis and A. mangium monocultures: the 21% lower growth (ΔB(w)) in A100 compared with E100 was almost entirely explained by a 23% lower GPP, with little or no species difference in ratios such as TBCF/GPP, ANPP/TBCF, ΔB(w)/ANPP and ΔB(w)/GPP. In contrast, the 28% lower ΔB(w) in MS than in E100 was explained both by a 15% lower GPP and by a 15% lower fraction of GPP allocated to wood growth, thus partially supporting our second hypothesis: mixing the two species led to shifts in C allocations from above- to belowground, and from growth to litter production, for both species.

Response of Grass Seedlings to Smoke-Water and Smoke-Derived Butenolide in the Absence of Macronutrients (Nitrogen, Phosphorus, and Potassium)

Abstract Compositional transformation of South African semiarid grasslands and savannas owing to changes in soil nutrient status and fire-linked attributes is often reported. However, mechanisms of change are not fully understood. Currently, plant-derived smoke has attracted much attention as a fire-related cue responsible for stimulating germination and seedling growth. However, there is very little documentation on how these fire-linked factors, such as smoke, and soil macronutrients, such as nitrogen (N), phosphorus (P), and potassium (K), interact to effect seedling growth of grasses. In this study, smoke-responsive ( Themeda triandra ) and less smoke-responsive species ( Eragrostis curvula and Panicum maximum ) were tested with different concentrations and combinations of smoke-water and smoke-isolated butenolide with or without added N, P, or K under greenhouse conditions. In the absence of N, P, or K, smoke-water and butenolide treatments enhanced a number of seedling growth parameters of T. triandra . In contrast, exclusion of N from the nutrient solution significantly reduced shoot length, seedling weight, root volume, and vigor index of E. curvula at all tested concentrations of smoke-water and butenolide solutions compared to the control. In the presence of N, P, and K, smoke-water and butenolide suppressed seedling growth of P. maximum , whereas the absence of one of these macronutrients had a small promotory effect on some parameters. This study may assist in understanding the postfire seedling dynamics of grasses.

Sugar maple growth in relation to nutrition and stress in the northeastern United States

Sugar maple, Acer saccharum, decline disease is incited by multiple disturbance factors when imbalanced calcium (Ca), magnesium (Mg), and manganese (Mn) act as predisposing stressors. Our objective in this study was to determine whether factors affecting sugar maple health also affect growth as estimated by basal area increment (BAI). We used 76 northern hardwood stands in northern Pennsylvania, New York, Vermont, and New Hampshire, USA, and found that sugar maple growth was positively related to foliar concentrations of Ca and Mg and stand level estimates of sugar maple crown health during a high stress period from 1987 to 1996. Foliar nutrient threshold values for Ca, Mg, and Mn were used to analyze long-term BAI trends from 1937 to 1996. Significant (P < or = 0.05) nutrient threshold-by-time interactions indicate changing growth in relation to nutrition during this period. Healthy sugar maples sampled in the 1990s had decreased growth in the 1970s, 10-20 years in advance of the 1980s and 1990s decline episode in Pennsylvania. Even apparently healthy stands that had no defoliation, but had below-threshold amounts of Ca or Mg and above-threshold Mn (from foliage samples taken in the mid 1990s), had decreasing growth by the 1970s. Co-occurring black cherry, Prunus serotina, in a subset of the Pennsylvania and New York stands, showed opposite growth responses with greater growth in stands with below-threshold Ca and Mg compared with above-threshold stands. Sugar maple growing on sites with the highest concentrations of foliar Ca and Mg show a general increase in growth from 1937 to 1996 while other stands with lower Ca and Mg concentrations show a stable or decreasing growth trend. We conclude that acid deposition induced changes in soil nutrient status that crossed a threshold necessary to sustain sugar maple growth during the 1970s on some sites. While nutrition of these elements has not been considered in forest management decisions, our research shows species specific responses to Ca and Mg that may reduce health and growth of sugar maple or change species composition, if not addressed.

The pre-Colombian footprint on terrestrial nutrient cycling in Costa Rica: insights from phosphorus in a lake sediment record

The impact of pre-Columbian subsistence agriculture on soil nutrient cycling in the American tropics is poorly quantified. Paleolimnological research can address this deficit by documenting the temporal evolution of nutrient cycling in lake watersheds over different time scales. Here we describe our use of a chemical sequential extraction technique adapted from soil fertility research to discern geochemical fractions of phosphorus (P) in lake sediments that serve as proxies for landscape-scale soil nutrient status. These P fractions are mineral P (the original lithic source of bioavailable P), occluded P (mainly bound to soil oxides), and organic P (remains of organic matter production by plants). We applied the P fractionation technique to a lake sediment core from a small lake in southern Costa Rica, Laguna Zoncho. Prior analyses of microfossils and stable carbon isotopes in this core documented an approximately 3,000 year history of human occupation and agricultural activity in the Zoncho watershed, and shifts in diatom communities in the lake associated both with human impacts and with climate-driven changes in lake level. Our P analyses revealed relatively constant P geochemistry during the first approximately 2,500 years of the record, when other sedimentary proxies reveal forest clearance and maize agriculture of varying intensity. However, the period from approximately 500 to 100 years BP is marked by a drastic shift toward a P geochemistry dominated by occluded forms, with a concomitant decrease in the relative content of both the organic and mineral P forms. This interval coincides with post-Conquest depopulation and forest regeneration at the site, and with an apparent deepening of the lake caused by a shift toward a wetter climate. The dominance of the occluded P fraction during this interval is the opposite of the trend expected with such a climate shift, implicating human dynamics as the principal driver of the changes in soil nutrient status indicated by the P fractions in the Zoncho core. We propose that the entire P geochemical record is dominated by human-induced alteration of the soil nutrient cycles via agriculture and occupation, and that the only interval that reveals the “natural” nutrient status in the region is the short interval when the site is abandoned and surrounding forests regrow. These results for Laguna Zoncho reveal the close connection between even relatively low-technology human activities and soil nutrient status.

Effects of elevated carbon dioxide and nitrogen fertilization on nitrate reductase activity in sweetgum and loblolly pine trees in two temperate forests

Nitrogen (N) availability is a major factor limiting plant production in many terrestrial ecosystems and is a key regulator of plant response to elevated CO2. Plant N status is a function of both soil N availability and plant N uptake and assimilation capacity. As a rate-limiting step in nitrate assimilation, the reduction of nitrate is an important component of plant physiological response to elevated CO2 and terrestrial carbon sequestration. We examine the effects of elevated CO2 and N availability on the activity of nitrate reductase, the enzyme catalyzing the reduction of nitrate to nitrite, in two temperate forests—a closed canopy sweetgum (Liquidambar styraciflua) plantation in Tennessee (Oak Ridge National Laboratory (ORNL)) and a loblolly pine (Pinus taeda) stand in North Carolina (Duke). Both CO2 and N enrichment had species specific impacts on nitrate reductase activity (NaR). Elevated CO2 and N fertilization decreased foliar NaR in P. taeda, but there were no treatment effects on L. styraciflua NaR at ORNL or Duke. NaR in 1-year P. taeda needles was significantly greater than in 0-year old needles across treatments. P. taeda NaR was negatively correlated with bio-available molybdenum concentrations in soils, suggesting that CO2 and N-mediated changes in soil nutrient status may be altering soil-plant N-dynamics. The variation in response among species may reflect different strategies for acquiring N and suggests that elevated CO2 may alter plant N dynamics through changes in NaR.

The influence of soil properties on the structure of bacterial and fungal communities across land-use types

Land-use change can have significant impacts on soil conditions and microbial communities are likely to respond to these changes. However, such responses are poorly characterized as few studies have examined how specific changes in edaphic characteristics do, or do not, influence the composition of soil bacterial and fungal communities across land-use types. Soil samples were collected from four replicated ( n = 3) land-use types (hardwood and pine forests, cultivated and livestock pasture lands) in the southeastern US to assess the effects of land-use change on microbial community structure and distribution. We used quantitative PCR to estimate bacterial–fungal ratios and clone libraries targeting small-subunit rRNA genes to independently characterize the bacterial and fungal communities. Although some soil properties (soil texture and nutrient status) did significantly differ across land-use types, other edaphic factors (e.g., pH) did not vary consistently with land-use. Bacterial–fungal ratios were not significantly different across the land-uses and distinct land-use types did not necessarily harbor distinct soil fungal or bacterial communities. Rather, the composition of bacterial and fungal communities was most strongly correlated with specific soil properties. Soil pH was the best predictor of bacterial community composition across this landscape while fungal community composition was most closely associated with changes in soil nutrient status. Together these results suggest that specific changes in edaphic properties, not necessarily land-use type itself, may best predict shifts in microbial community composition across a given landscape. In addition, our results demonstrate the utility of using sequence-based approaches to concurrently analyze bacterial and fungal communities as such analyses provide detailed phylogenetic information on individual communities and permit the robust assessment of the biogeographical patterns exhibited by soil microbial communities.

The Representative Soil Sampling Scheme of England and Wales: a statistical analysis of topsoil nutrient status and pH between 1971 and 2001

AbstractThe Representative Soil Sampling Scheme of England and Wales has recorded information on the soil of agricultural land in England and Wales since 1969. It is a valuable source of information about the soil in the context of monitoring for sustainable agricultural development. Changes in soil nutrient status and pH were examined over the period 1971–2001. Several methods of statistical analysis were applied to data from the surveys during this period. The main focus here is on the data for 1971, 1981, 1991 and 2001. The results of examining change over time in general show that levels of potassium in the soil have increased, those of magnesium have remained fairly constant, those of phosphorus have declined and pH has changed little. Future sampling needs have been assessed in the context of monitoring, to determine the mean at a given level of confidence and tolerable error and to detect change in the mean over time at these same levels over periods of 5 and 10 years. The results of a non‐hierarchical multivariate classification suggest that England and Wales could be stratified to optimize future sampling and analysis. To monitor soil quality and health more generally than for agriculture, more of the country should be sampled and a wider range of properties recorded.

Intercropping and Crop Residue Incorporation: Effects on Soil Nutrient Status

ABSTRACT A maize-melon mixture relayed into a cassava-soybean intercrop was established at Ibadan, Nigeria, between 1995 and 1997 in order to study the changes in soil-nutrient status, that occurred due to soybean intercropping and residue incorporation. The experiment was conducted on a Kanhaplic Haplustalf soil. Soybean was planted in drills between cassava rows after harvesting maize and melon. Soybean stover was recycled into half of the soybean plots. Cassava yield was reduced by about 16% with soybean intercropping without the residue incorporation and by about 11% with incorporation of the crop residue. Soil pH was significantly reduced from an initial 6.0 to 5.7 with soybean intercropping. Organic matter was drastically reduced from an initial 31.0 g kg−1 to 5.3 g kg−1 with sole cassava cropping, and to 10.1 g kg−1 with soybean intercropping and incorporation of crop residue. Total nitrogen (N) was also significantly reduced to about 0.4 g kg−1from an initial content of 1.8 g kg−1, while the available phosphorus (P) was increased from 1.8 to an average of 4.0 mg kg−1. The exchangeable potassium (K) and effective cation-exchange capacity (ECEC) were not significantly affected.

SOIL NUTRIENT CHANGES WITH FERTILIZER TYPE IN CASSAVA-BASED CROPPING SYSTEM

ABSTRACT The changes in soil nutrient status following the application of different fertilizer types were studied in field experiments involving maize-melon intercrop relayed into a cassava-soybean intercrop between 1995 and 1997. The soil at the experimental site was a Kanhaplic Haplustalf, which was under continuous cultivation with arable crops for seven years and fallow for four years. The effects of organic and inorganic fertilizers were investigated singly and in combination. The type of fertilizer had no significant effect on the soil pH, although, cropping significantly lowered the pH from 6.0 to 5.7. Cropping also significantly reduced the soil organic matter and total nitrogen (N). The soil organic matter (OM) and total N were most depleted with organic fertilizer application. Complementary application of organic and inorganic fertilizers limited the degree of depletion from 31.0 to 12.1 g kg−1 of OM and 1.8 to 0.6 g kg−1 total N. Soil available P was increased (60%) by inorganic fertilizer while the organic fertilizer increased it by 145% and the combined fertilizer by 186%. Exchangeable calcium (Ca) was depleted by about 12% with organic fertilizer application, 15% by inorganic fertilizer and about 19% with complementary application of organic and inorganic fertilizers. Exchangeable sodium (Na) was reduced from 0.43 to about 0.38 cmol kg−1 while magnesium (Mg) was increased from 0.5 to about 0.6 cmol kg−1.

Effect of planting method, tillage and weed management on productivity and wheat (Z'riticurn aestivum&gt; ghysico-chemical properties of rice (Oryza sativa) - cropping system

A field experiment was conducted during 2002-03 and 2003-04 at Raipur in Chhattisgarh to assess the produc- tivity of rice (Oryza sativa L.) -wheat [Piticum aestivum L. emend. Fiori &amp; Paol.] cropping system and changes in soil-nutrient status due to different planting methods of rice and tillage and weed-management practices of wheat. Transplanting of rice after Sesbania aculeata (green manure, GM) incorporation (Rice,,,,) produced significantly higher grain yield of rice (19.5-25.3%) and increased the organic C, available N and K over transplanting of rice (Rice,,) and beushening system without GM (Rice,,). The residual effect of Rice ,,,, gave 11 .I % higher grain yield of wheat, increased the available N, P and K content in the soil and reduced the bulk density in 0-7 and 10-17 cm soil depths. Conventional tillage (Wheat,,) in wheat produced 19.1% higher grain yield than zero tillage (Wheat,). Zero-tilled wheat gave 10.7% higher organic C in the soil than Wheat ., Infiltration rate was the highest under Wheat,, and observed to be 20.5% higher at harvest. Post-emergence application of sulfosulfuron @ 25 g/ ha and metsulfuron-methyl @ 4 glha reduced the dry weight of weeds significantly over the weedy check and in- creased the grain yield of wheat. Transplanting of rice after GM incorporation followed by conventional tillage and in post-emergence application of ~ ~ l f ~ ~ ~ l f i ~ r o r l wheat improved the soil physico-chemical properties and gave the maximum total productivity (12.45 tiha) and net returns (Rs 52,104lha).