Semi-arid Tropical Soils Research Articles

Can gypsum and organic amendments achieve sustainability, productivity and maintain soil health under soybean-mustard cropping in sodic soils of western India

Soil salinity is a major environment stress impairing crop production and accelerating soil degradation. Use of soil amendments are practical solutions for altering soil quality to enhance crop productivity in these soils. Hence, we systematically evaluated the impact of soil amendments practices on crop productivity, nutrient use efficiency, soil properties, soil quality index, economics and energetics on soybean-mustard cropping system in sodic Vertisol. In this study, eight treatments comprising of various combinations of soil amendments such as gypsum (@2.5 t ha−1), farmyard manure (FYM@10 t ha−1), crop residue (CR@1.5 t ha−1 of soybean residue during rabi and 3 t ha−1 of mustard residue during kharif season) with recommended fertilizer doses (RNPK) was evaluated in randomized block design with three replications for four consecutive years in soybean-mustard cropping sequences (2016–2019). Results demonstrated that application of gypsum with CR and FYM recorded a significant drop in exchangeable sodium percentage (ESP) (45–48 %), and bulk density (BD) (3–6 %) than that of control. Organic amendment in conjunction with gypsum and chemical fertilizer significantly improved soil chemical, physical and biological properties than that under control and inorganic fertilizer alone treatments. Based on principal component analysis and correlation matrix, minimum data set identified ESP, pH, BD, organic carbon, available nutrients, biomass carbon, calcium content, dehydrogenase as the most important properties controlling soil quality. Integration of RNPK+Gypsum+CR and RNPK+Gypsum+FYM are found superior leading to higher crop yield in soybean (1.23 and 1.21 Mg ha−1 respectively), mustard (1.43 and 1.39 Mg ha−1 respectively), better nutrient recovery efficiency (77 and 53 % respectively), improved soil quality index (0.90 and 0.93 respectively), and higher economic return (benefit: cost ratio-2.88 and 2.1 respectively).Therefore, this study findings highlighted the conjunctive use of gypsum with organic amendments is effective in reclaiming salt stress, improving soil health and crop productivity under oilseed cropping sequence in degraded soils of semi-arid tropics.

Improving grain quality and nitrogen use efficiency of cereal-based cropping systems on vertisols in semi-arid tropics

ContextSemi-arid tropics is facing serious issues of malnutrition in population owing to poor quality of food grain production. Malnutrition is directly linked to lower grain protein and zinc yield due to inappropriate land and water, and nutrient management practices, which also resulted into reduced nitrogen use efficiency (NUE) in cereals. ObjectiveThe objectives of the study were to evaluate the effect of land and water and nutrient management on grain protein and zinc yield, and NUE of cereal-based cropping systems on vertisols soils in semi-arid tropics. MethodsThe study was carried out at Hyderabad in India during 2014–15 and 2015–16 and involved three cropping systems (two rotation systems: sorghum-chickpea and maize-groundnut; and one intercropping: pearl millet + pigeonpea), two land and water management i.e. flatbed and broad bed furrows and four nutrient management-N1: Control (no fertilizer), N2: 100% recommended application of macronutrient (nitrogen, phosphorus and potassium) through chemical fertilizer, N3: N2 + 100% recommended application of secondary nutrient (sulphur) and micronutrient (zinc and boron) through chemical fertilizer, and N4 (integrated nutrient): 50% of N2 + 50% nitrogen in cereals or phosphorus in legumes through organic fertilizer as vermicompost. ResultsIn sorghum-chickpea rotation system, the treatment interaction broad bed furrows with 100% recommended application of macronutrient, secondary nutrient and micronutrient recorded significantly higher grain zinc yield in both the years, while grain protein yield was significantly higher in second year. The grain protein and zinc yield in sorghum-chickpea rotation system, and agronomic nitrogen use efficiency in pearl millet+pigeonpea intercropping system was significantly higher in broad bed furrows than flatbed. The agronomic NUE of broad bed furrows was higher by 61% in 2014–15 and 65% in 2015–16 over flatbed. Among the nutrient management treatments, grain protein and zinc yield, and agronomic NUE were significantly higher in combined application of macronutrient, secondary nutrient, and micronutrients through chemical fertilizer i.e. N3 followed by N4, N2 and N1. ConclusionThe broad bed furrows and application of macronutrient, secondary nutrient and micronutrient could be an effective integrated land and water and nutrient management approach to improve grain quality and agronomic nitrogen use efficiency of cereal-based cropping systems in semi-arid tropics. ImplicationsThis study contributed to develop integrated land and water and nutrient management as an innovative agronomic management practice for cereal-based cropping systems, which needs to scale-up through Government agricultural policies to overcome the issue of malnutrition in population living in semi-arid tropics.

Use of soil test kits in assessing soil fertility of castor growing soils of semi-arid tropics

Resource poor farmers use semi-arid tropic soils of southern India for castor cultivation. These soils are wellknown for their low soil fertility thus resulting in poor castor seed yield. Conventional soil tests of laboratory willtake more time. Based on these, fertiliser recommendations to the farmers is seldom delivered in time. Soil test kits (STKs) developed by Acharya N G Ranga Agricultural University, Hyderabad and Coromandal Fertilisers Ltd.,Secunderabad is quiet handy in determining the physico-chemical properties on the spot and advice fertiliserrecommendations to the farmers. In the present study, results obtained by using these STKs and conventionallaboratory testswere compared. The parameters viz., pH, organic carbon, available nitrogen, phosphorus, potassium, sulphur and micronutrients (zinc, boron and iron) were in close agreement with that of laboratory tests. Thus, for a quick diagnosis of soil fertility status, STKs are highly useful and accordingly fertiliser recommendations can be given to farmers.

Assessing land use type impacts on soil quality: Application of multivariate statistical and expert opinion-followed indicator screening approaches

Knowledge on the influence of land use practices on soil quality is crucial to develop soil-specific management practices. In order to quantify soil quality index of different land use types in Hintalo Wajerat district of northern Ethiopia, twenty-three biochemical and physical soil attributes were measured at 0–30 cm depth from cultivated land (CL), grass land (GL) and shrub land (SL). Principal component analysis (PCA), discriminant analysis (DA) and expert opinion (EO) were used for minimum data sets (MDS) selection, and six soil quality indices were generated using linear (LS) and non-linear (NLS) scoring methods. One-way analysis of variance (ANOVA) was used to identify members of total data set. Results indicated a significant (p < 0.05) difference in soil quality index among the land use types with a definite trend in the following increasing order of SL > GL > CL, reflecting the need for improved managements in CL soils. The estimated soil quality index using NLS indicator transformation and DA indicator selection approach (SQI_NLS_DA) best distinguished soil functions related to varying land use types. The findings of this study indicated the significant influence of land use practices on soil quality and SQI_NLS_DA is suggested for future soil quality studies in semi-arid tropical soils.

Nutrient management and cropping pattern influence the carbon sequestering ability of semi-arid tropical soils

Nutrient management and cropping pattern influence the carbon sequestering ability of semi-arid tropical soils

Bacterial derived biopolymer to alleviate nutrient stress and yield enhancement in turmeric (Curcuma longa L.) by mediating physiology and rhizosphere microbes on poor soils of semi-arid tropics

ABSTRACT Biopolymers (BP) are the unexploited eco–friendly microbial derivatives which regulate soil moisture and nutrient mobility. Therefore, a field experiment was conducted for two years (2017–18 and 2018–19) to determine the beneficial effects of BP in reducing nutrient stress and yield enhancement in turmeric. The study was laid out in a split-plot design with each of four levels of nutrients (control, 50%, 75%, and 100% of Recommended Dose of Nutrients; RDN) and BP (0, 2.5, 5.0, and 7.5 kg ha–1). Results indicated that BP application (7.5 kg ha–1) significantly improved the soil moisture content (40.31%) and microbial colonization (total microbes, N fixers, and P solubilizers). As a result, combined application BP with either 75% or 100% of RDN enhanced the photosynthesis (22.95–24.50 μmol m−2 s−1) and lowered the canopy temperature (24.47–24.67°C) of turmeric. Thus, higher yield (7.05–7.82 t ha−1) and partial factor productivity were achieved. Supplementing BP with 100% RDN enhances the turmeric yield by up to 29–49% over 100% RDN alone. Therefore, biopolymer maintains the equivalent turmeric yield of 100% RDN even at 25–50% less nutrients in the nutrient-poor soils of semi-arid Tropics.

Standardisation of Assay of L-glutaminase Activity in Arid and Semi Arid Tropical Soils of South India

Standardisation of Assay of L-glutaminase Activity in Arid and Semi Arid Tropical Soils of South India

Impact of long-term nutrient management on sequestration and dynamics of soil organic carbon in a semi-arid tropical Alfisol of India

We aim to determine the effect of long term application of organic and inorganic nutrients on carbon sequestration and related biological attributes of a semi-arid tropical soil under an intensive maize-sunflower cropping system in India. The century-old experimental soil was assessed the impact of nutrient management on carbon sequestration, labile and passive pools of soil organic carbon, and soil biological attributes. The topsoil (0–25 cm) and subsoil (25–50 cm) samples from unfertilized (control), chemical fertilizer applied (IC), organic manure amended (OM), and integrated nutrient management adopted (INM) plots were analyzed for carbon sequestration and dynamics. The INM and OM treatments had a mean annual carbon sequestration rate of 0.18 Mg and 0.14 Mg carbon per ha, respectively. The continuous addition of organic amendment (12.5 t ha−1 year−1 of farmyard manure) with or without chemical fertilizer improved both topsoil and subsoil active carbon pools viz., microbial biomass carbon, labile carbon, water-soluble carbon, particulate carbon fraction, and passive pools like humic acid and fulvic acid significantly compared to synthetic fertilizer and unfertilized treatments. The Fourier-transformed infrared spectra of humic acids extracted from OM and INM treatment soils showed high humification, aromaticity, and redox with complex functional groups than IC and control treatment soils. OM and INM treatments significantly enhanced the abundance of carbon mineralizing gene (chiA) in topsoil and subsoil than IC and control treatments, while the carbon dioxide fixing gene (cbbL) had no apparent change due to nutrient management. Subsequently, the organics amended soils had better biological quality in terms of higher soil enzymes' activity, bacterial abundance, and respiration rate with lower metabolic quotient than chemical fertilized and control soils. The principal component analysis indicated that OM and INM treatment soils were distinctly positioned from IC and control treatment soils and the soil carbon fractions and soil enzymes were the significant factors influencing the nutrient management induced carbon sequestration. The active and passive carbon fractions, dehydrogenase, fluorescein diacetate hydrolysis, alkaline phosphatase, and substrate-induced respiration showed a strong and positive correlation with carbon sequestration of semi-arid tropical soil. Altogether, these findings indicated that the continuous addition of organic amendments would be a valuable practice to improve the soil carbon sequestration and carbon pools, and this practice is essential for the tropical soils with intensive farming to sustain the soil quality and agricultural productivity.

Development of a soil biological quality index for soils of semi-arid tropics

Abstract. Agricultural intensification, an inevitable process to feed the ever-increasing population, affects soil quality due to management-induced changes. To measure the soil quality in terms of soil functioning, several attempts were made to develop a soil quality index (SQI) based on a set of soil attributes. However, there is no universal consensus protocol available for SQI, and the role of soil biological indicators in SQI is meagre. Therefore, the present work aims to develop a unitless soil biological quality index (SBQI) scaled between 0 and 10, which would be a major component of SQI in the future. The long-term organic manure amended (OM), integrated nutrient management enforced (INM), synthetic fertilizer applied (IC), and unfertilized control (control) soils from three different predominant soil types of the location (Tamil Nadu state, India) were chosen for this. The soil organic carbon, microbial biomass carbon, labile carbon, protein index, dehydrogenase activity, and substrate-induced respiration were used to estimate the SBQI. Five different SBQI methods, viz. simple additive (SBQI1 and SBQI2), scoring function (SBQI3), principal component analysis-based statistical modelling (SBQI4), and quadrant-plot-based method (SBQI5), were developed to estimate the biological quality as a unitless scale. All five methods have the same resolution to discriminate the soils and INM ≈ OM &gt; IC &gt; control is the relative trend being followed in all the soil types based on the SBQIs. All five methods were further validated for their efficiency in 25 farmers' soils of the location and proved that these methods can scale the biological health of the soil. Among the five SBQIs, we recommend SBQI5, which relates the variables to each other to scale the biological health of the soil.

Gross nitrogen transformation rates in semiarid tropical soils under different salinity and vegetation conditions

AbstractExacerbated inundations and saltwater intrusions due to sea‐level rise can significantly alter the ecology of low‐lying coastal drylands by affecting their nutrient cycling and productivity. During the present study, controls on production and consumption of nitrogen in soils of semiarid tropical climate with different levels of vegetation–salinity–moisture condition were investigated using 15N isotope dilution experiments. For this purpose, soils were collected from five land types including two in salt flat and one each in grassland (GL), wetland (WL), and an agricultural field. Soils with no vegetation, high salinity, and high moisture (salt flats) showed significant decline in gross production of nitrogen (mineralization rate: 0.21 ± 0.10 mg N·kg−1·d−1; nitrification rate: 0.27 ± 0.17 mg N·kg−1·d−1) compared to soils with vegetation, low salinity, and low moisture (GL, WL, and agricultural) (mineralization rate: 2.47 ± 1.74 mg N·kg−1·d−1; nitrification rate: 1.43 ± 1.30 mg N·kg−1·d−1). Backward stepwise regression analysis of the results indicated salinity to be the most important factor controlling nitrogen transformation rates. It is likely that soils undergoing frequent seawater exposure or excessive evaporation may experience slowdown in nitrogen cycling due to salinization leading to reduced nutrient production and consumption. Due to climate change, the areal extent of coastal drylands undergoing such decline in nutrient production is likely to increase, eventually leading to loss of productivity and desertification.

Diagnosis of multinutrients deficiency in rainfed semi-arid tropical soils of Karnataka

Diagnosis of multinutrients deficiency in rainfed semi-arid tropical soils of Karnataka

Soil Resilience and Sustainability of Semi-Arid and Humid Tropical Soils of India: A Commentary

Soil is a dynamic and living natural resource, which supports to produce goods and services of value to humans but not necessarily with perpetual ability against the degradative processes. It is well known that soil formation is a slow process, and a substantial amount of soil can form only over a geologic timescale. Soil misuse and extreme climatic conditions can damage self-regulating capacity and give way to regressive pedogenesis (Pal et al. 2013), and thus might lead to the soil to regress from higher to lower usefulness and or drastically diminished productivity. Such an unfavorable transformation of soils is termed as ‘soil degradation'. However, soils do have an inherent ability to restore their life support processes if the disturbances created by anthropogenic activities are not too drastic and sudden, and mitigated with enough time is allowed for life-support processes to restore themselves. This intrinsic ability of soils to regenerate their productivity is called resilience (Szabolcs 1994). Therefore, soil resilience is the ability to bounce back or return to normal functioning, after adversity, for sustainable productive purposes.

Carbon and Nitrogen Dynamics of Soil Organic Matter Fractions in Thickets and Intergrowth Areas of Sudanian Savannah Grasslands, Bondoukuy, Western Burkina Faso

Soil organic carbon (SOC) and total nitrogen (TN) play a central role in physico-chemical fertility of a soil, and thus promoting agricultural productivity. Yet little is known about SOC and TN dynamics in tropical ferruginous soils of Sub-Saharan Africa. In this study, thicket and intergrowth soil samples, under both cultivation and perennial grass fallow (Andropogon gayanus), were collected in Bondoukuy, western Burkina Faso. The samples were fractionated and their SOC and TN contents in six organo-mineral fractions were analyzed. Because of the high labile organic matter pools in coarse sand fractions, SOC (~630 &amp;micro;g C g &amp;ndash;1 soil) associated with these fractions appeared to be more accessible to soil microbes than recalcitrant and occluded pools (~440 &amp;micro;g C g &amp;ndash;1 soil) within the fine fractions of the fallow soils. The results also indicated that clay fractions are likely to represent a source of the available nitrogen to crop following long fallow periods (~20 years). In contrast, the differences in TN contents were not significant (p&amp;gt;0.05) between ploughed plots and young fallow lands (~10 years). The substantial decrease in C/N ratios from coarse particulate organic matter pools (C/N=68) to fine pools (C/N=10) suggested an increase in the SOC decomposition rate in the fine fractions. This indicates a substantial decrease in microbial activities following a reduction in particulate organic matter sizes. The SOC contents were relatively high in coarse (~930 &amp;micro;g C g &amp;ndash;1 soil) fractions of the thicket soils compared to those of the adjacent intergrowth soils (~620 &amp;micro;g C g &amp;ndash;1 soil). A similar SOC distribution pattern was also observed in fine fractions of the thicket and the intergrowth soils. Total nitrogen also exhibited a high distribution pattern in fine sand and very fine sand fractions. The findings of this study demonstrated that SOC and TN restoration in semi-arid tropical savannah soils is a function of particulate organic matter sizes, vegetation type and soil management practices.

Evaporation trends on intervening period for different wheat establishments under soils of semi-arid tropics

Evaporation trends on intervening period for different wheat establishments under soils of semi-arid tropics

Effect of Graded Levels of Surface Crop Residue Application Under Minimum Tillage on Carbon Pools and Carbon Lability Index in Sorghum (Sorghum bicolor (L.) Moench)-Cowpea (Vigna unguiculata) System in Rainfed Alfisols

ABSTRACTA long term experiment (2005–2012) was conducted in rainfed semi-arid tropical Alfisol at Hayathnagar Research Farm of Central Research Institute for Dryland Agriculture, Hyderabad, India. The aim of this experiment was to study the long-term impacts of graded levels of surface crop residue application on carbon (C) pools, aggregate associated C, C lability index and their relationship with crop yield. The experiment was conducted in a randomized block design (RBD) with minimum tillage (MT). Experimental treatments comprised of four levels of surface application of sorghum crop residues (@ 0, 2, 4 and 6 t ha−1). The test crops, sorghum and cowpea, were grown in rotation yearly. Based on the pooled analysis of long term data (2005–2012), the study revealed that the surface application of sorghum residue @ 6 t ha−1 and 4 t ha−1 recorded 21% and 16% higher sorghum grain yields, respectively over control (no residue) whereas, the corresponding increase in the cowpea yield was 50% and 60%, respectively. Besides, the concentrations of soil organic carbon (SOC), inorganic carbon (IC), total carbon (TC), particulate organic carbon (POC) in the top surface soil (upper layer, 0–5cm depth) were found significantly higher than the sub-surface soil (lower layers, 5–15 cm depth) in all the treatments. Storage of soil C was assessed in soil aggregates fractions, and it was found that the smaller size aggregate fractions (0.053mm) contained significantly (p = 0.05) higher content of SOC compared to the large sized fractions (2 mm). The amount of very labile fraction of C extracted with 12 N H2SO4 was significantly higher (1.04 g kg−1) with the application of sorghum stover @ 6t ha-1 compared to other residue level treatments, in the 0-5 cm soil layer. The Lability Index (LI) increased with the increase in the amount of residues applied and was significantly higher in the surface soils compared to subsurface soil. The results of this study will be highly relevant and of significant value from the view point of managing SOC and its different pools in soil under abiotically stressed semiarid tropical Alfisols soils.

Sustaining Soil Quality, Resilience and Critical Carbon Level under Different Cropping Systems in Semi-Arid Tropical Alfisol Soils

Subsistence agriculture practice and a combination of harsh climate and fragile soils along with increasing demographic pressure are matters of great concern from the viewpoint of resource management and longterm sustainability in the semi-arid tropical Alfisol soils of India. In this study, soil quality index (SQI) has been computed on 190 sites of farmers' fields in southern India to evaluate the possible effect of land management practices on soil degradation and determine the critical levels of soil organic C stock to maintain a desirable SQI and also suggest appropriate management practices. In all, 26 predominant physical, chemical and biological properties of soils were studied and based on principal component analysis, moisture retention at field capacity, available soil N, available P, DTPA-extractable Zn, exchangeable sodium percentage, C-mineralization and bulk density were identified as the key indicators of the study region. SQI was also computed using four soil functions, viz. nutrient cycling, availability of water, resistance of soil to degradation, and salinity and sodicity. Soil resilience index was computed using data on substrateinduced respiration after exposing the soil to heat stress. SQI was highest under paddy followed by permanent fallow, maize, cotton, intercropping, redgram, and was lowest under castor system. Based on the results, it was observed that the soils which had higher SQI were also productive and they exhibited higher resilience capacity. An amount of 8.6 Mg ha -1 soil organic C stock per 15 cm depth was found essential to maintain soil quality and 2.2 Mg ha -1 of organic matter was needed every year to maintain this stock. On-farm participatory research trial was conducted using SQI as a tool for sustainable land-management practices.

How Fertile are Semi-Arid Tropical Soils?

The semi-arid tropical (SAT) regions are notably characterized by low rainfall and high temperatures, and hence low natural primary productivity and soil fertility. However, to adequately respond to the title of our article as to how fertile are SAT soils, there is a need to critically review the current literature on the fertility status of SAT soils. Little attention has been paid in the past to determining the fertility status of SAT soils supporting rainfed production systems despite the fact that the SAT soils are relatively fragile than their irrigated counterparts; and this is due to their widespread degradation and lack of investment in building up the fertility. However, as in the case of other agroecosystems, the soils in the SAT regions vary widely in various fertility parameters. For example, the results of survey of large numbers of farmers’ fields in the SAT regions of India, by the ICRISAT and its partners, showed that they vary widely in soil pH, salts (electrical conductivity, EC), organic C (an index of available N) and major (N and P), secondary (S) and micronutrients (B and Zn) although the soils were low in organic C with widespread deficiencies of these nutrients. From the results discussed in this article, it is concluded that in general, the soils in the SAT regions are low in fertility; however, they vary widely in various fertility parameters.

Resilience of the Semi-Arid Tropical Soils

Soils in the semi-arid tropics (SAT) are subject to chemical degradation mostly due to climatic reasons which make the pedo-environment hostile to form calcium carbonate. This triggers an overall deterioration of soil properties affecting its physical and chemical parameters. Such soils require management interventions which may include chemical and other phytoremediation process. The present paper details this process of degradation in light of resilience of these soils of SAT.

Zinc Solubilizing Potential of Enterobacter cloacae Strain ZSB14 in Three Different Semi-arid Tropical Soils

Microbial transformation of soil unavailable zinc (Zn) into available form is an important agronomical approach not only to alleviate the Zn deficiency of stable food crops but also to improve the nutritional quality of human diet. Zinc solubilizing bacteria (ZSB) as an inoculant to the crop plants could be a sustainable input for Zn-fertilization as well as for Zn-biofortification. In order to explore these bacteria, we have conducted a microcosm study to assess its potential in terms of Zn availability in three different soils of semi-arid tropics and its interaction effects with different insoluble Zn amendments.....

Genesis, classification and evaluation of cotton growing soils in semi arid tropics of Tamil Nadu

The study was carried out in the new research station of Tamil Nadu Agricultural University at Cotton Research Station, Veppanthatai of Perambalur district of Tamil Nadu was selected for developing the strong soil resource database for proper appraisal of their productivity potential and their rational use. This study was an embodiment with an objective of characterization, classification and evaluation of some black cotton soils in semi arid tropical region of Tamil Nadu. The black soils of CRS, Veppanthattai were formed at nearly level to plain topography on granitic gneiss parent material mixed with calcareous murram. The soil colour varied from very dark gray to dark grayish brown under dry and moist condition, respectively. The soils were very deep. The textural class of fine earth fraction was clayey and had coarse strong angular blocky structure. The clay content ranged from 52.9 to 64.3 per cent. The silt content in most of the pedons showed an irregular trend with soil depth. The sand content varied from 19.7 to 30.1 per cent. Bulk density increased with increasing depth. The moisture retention at field capacity (33kpa), permanent wilting point (1500kpa) and available water capacity were high. The pH values ranged from moderately alkaline (8.48) to strongly alkaline (9.13). The electrical conductivity of the pedons ranged from 0.14to 0.72 dS m ?1 indicating that these soils were non-saline in nature. The organic carbonstatus was medium (5.4 to 5.5 g kg ?1 ) in surface horizons, whereas, in subsurface horizons it was low and ranged from 0.70 to 4.6g kg ?1 . The CaCO 3 content varied from 7.3 to 15.5 per cent. The cation exchange capacity of soilswas high [44.6 to 48.8 c mol (p + ) kg ?1 ]. The exchangeable bases were high and in the order of Ca +2 > Mg +2 > Na + > K + on the exchange complex. Based on the morphology, physical, physico-chemical, and chemical properties of the soils, pedons were classified as per USDA soil taxonomy into orders Vertisols . The soils are very deep and ideal for cultivation of cotton, sorghum, soybean, greengram, blackgram, redgram, sunflower, sesamum, maize and pearlmillet.