Double zero tillage and foliar phosphorus fertilization coupled with microbial inoculants enhance maize productivity and quality in a maize-wheat rotation

Regulation of tillage on grain matter accumulation in maize

Introduction

To address issues related to shallow soil tillage, low soil nutrient content, and single tillage method in maize production in the Western Inner Mongolia Region, this study implemented various tillage and straw return techniques, including strip cultivation, subsoiling, deep tillage, no-tillage, straw incorporation with strip cultivation, straw incorporation with subsoiling, straw incorporation with deep tillage, and straw incorporation with no tillage, while using conventional shallow spinning by farmers as the control.

Methods

We employed Xianyu 696 (XY696) and Ximeng 6 (XM6) as experimental materials to assess maize 100-grains weight, grain filling rate parameters, and grain nutrient quality. This investigation aimed to elucidate how tillage and straw return influence the accumulation of grain material in different maize varieties.

Results and discussion

The results indicated that proper implementation of tillage and straw return had a significant impact on the 100-grains weight of both varieties. In comparison to CK (farmer's rotary rotation), the most notable rise in 100-grains weight was observed under the DPR treatment (straw incorporation with deep tillage), with a maximum increase of 4.84% for XY696 and 6.28% for XM6. The proper implementation of tillage and straw return in the field resulted in discernible differences in the stages of improving the grain filling rates of different maize varieties. Specifically, XY696 showed a predominant increase in the filling rate during the early stage (V1), while XM6 exhibited an increase in the filling rates during the middle and late stages (V2 and V3). In comparison to CK, V1 increased by 1.54% to 27.56% in XY696, and V2 and V3 increased by 0.41% to 10.42% in XM6 under various tillage and straw return practices. The proper implementation of tillage and straw return had a significant impact on the nutritional quality of the grains in each variety. In comparison to CK, the DPR treatment resulted in the most pronounced decrease in the soluble sugar content of grains by 25.43% and the greatest increase in the crude fat content of grains by 9.67%.

Conclusion

Ultimately, the proper implementation of soil tillage and straw return facilitated an increase in grain crude fat content and significantly boosted grain weight by improving the grouting rate parameters at all stages for various maize varieties. Additionally, the utilization of DPR treatment proved to be more effective. Overall, DPR is the most promising strategy to improve maize yield and the nutritional quality of grain in the long term in the Western Inner Mongolia Region.

Productivity, soil health, and carbon management index of soybean-wheat cropping system under double zero-tillage and natural-farming based organic nutrient management in north-Indian plains

Conservation-agriculture and organic-farming are two sustainable-agriculture approaches to ensure food security and environmental-sustainability. Hence, a field study assessed the productivity, soil-health and carbon-dynamics of soybean-wheat cropping system (SWCS) under four tillage and residue-management practices (TRMPs) viz., Conventional-tillage without residues (CT-R), conventional-tillage with residue-retention in both crops at 3 t ha-1 each (CT + R), zero-tillage without residues (ZT-R), and zero-tillage with residue-retention in both crops at 3 t ha-1 each (ZT + R); and five organic-nutrient-management-practices (ONMPs) in both crops viz., 100 % RDF (N1), 100 % RDN through FYM (N2), 100 % RDN through VC (N3), 100 % RDN through FYM + Biofertilizers + Cow-urine + Panchgavya + Jeevamrut (N4), and 100 % RDN through VC + Biofertilizers + Cow-urine + Panchgavya + Jeevamrut (N5), in split-plot-design replicated-thrice. Among TRMPs, ZT + R enhanced system-productivity (SEY) by ∼17.2 % over CT-R, besides improved soil available-N, P, K by 6.4, 6.5 and 6.5 %, respectively. SMBC, SMBN and SMBP were higher under ZT + R by 16.2, 21.5 and 10.8 % over CT-R, respectively. ZT + R had higher soil enzyme activities of DHA, Acid-P, ALP, URA, and FDA over CT-R by 19.4, 20.7, 21.5, 20.7 and 15.2 %, respectively. ZT + R also had higher VLC, ACP, LI and CMI over CT-R. Among ONMPs, the natural-farming based ONMP, N5 considerably improved SMBC, SMBN, SMBP, FDA, DHA, Acid-P, URA, and ALP by 12.7-12.9 % over N1 (100 % RDF). ONMP-N5 improved the available-N, P, K content over N1 by 6.6, 5.8 and 6.7 %, respectively. ONMP-N5 had higher (p < 0.05) microbial-count, VLC, APC, LI and CMI; however, system-productivity was ∼4.1 % lower than N1 in this two-years' short-study which further need investigation in multi-location long-term experiments. Overall, the dual-crop basis ZT + R at 6 t ha-1 year-1 + NF-based ONMPs (N5) may harness higher and sustained productivity under SWCS besides advancing soil-health and soil carbon-pools in sandy-loam soils of north-Indian plains and similar soils across south-Asia.

High-value crops' embedded groundnut-based production systems vis-à-vis system-mode integrated nutrient management: long-term impacts on system productivity, system profitability, and soil bio-fertility indicators in semi-arid climate

The current study identified two new climate-resilient groundnut-based cropping systems (GBCSs), viz., groundnut-fenugreek cropping system (GFCS) and groundnut-marigold cropping system (GMCS), with appropriate system-mode bio-compost embedded nutrient management schedules (SBINMSs) for semi-arid South Asia. This 5-year field study revealed that the GMCS along with leaf compost (LC) + 50% recommended dose of fertilizers (RDF50) in wet-season crop (groundnut) and 100% RDF (RDF100) in winter-season crop (marigold) exhibited the highest system productivity (5.13-5.99 t/ha), system profits (US$ 1,767-2,688/ha), and soil fertility (available NPK). Among SBINMSs, the application of 5 t/ha leaf and cow dung mixture compost (LCMC) with RDF50 showed the highest increase (0.41%) in soil organic carbon (SOC) followed by LC at 5 t/ha with RDF50 and RDF100. Legume-legume rotation (GFCS) had significantly higher soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) than legume-non-legume rotations (groundnut-wheat cropping system (GWCS) and GMCS). Among SBINMSs, the highest SMBC (201 µg/g dry soil) and SMBN (27.9 µg/g dry soil) were obtained when LCMC+RDF50 was applied to groundnut. The SMBC : SMBN ratio was the highest in the GWCS. LC+RDF50 exhibited the highest SMBC : SOC ratio (51.6). The largest increase in soil enzymatic activities was observed under LCMC+RDF50. Overall, the GMCS with LC+RDF50 in the wet season and RDF100 in the winter season proved highly productive and remunerative with better soil bio-fertility. SBINMSs saved chemical fertilizers by ~25%' in addition to enhanced system productivity and system profits across GBCSs in semi-arid regions of South Asia. Future research needs to focus on studying the potential of diversified production systems on water and environmental footprints, carbon dynamics, and energy productivity under semi-arid ecologies.

Food-energy‑carbon nexus of Himalayan okra-pea cropping system: Impacts of AM-fungi, precision phosphorus and irrigation regimes in an acid Alfisol

Conventional farming practices are energy and carbon-intensive. Low-cost technologies like AM-fungi (AMF) and precision P-management vis-à-vis precision irrigation-scheduling may enhance P-bioavailability, and crop- and water-productivity with reduced energy and carbon-footprints in acid-Alfisol of north-western Himalayas. Hence, an experiment was done in okra (Abelmoschus esculentus)-pea (Pisum sativum) cropping system (OPCS) using AMF (Glomus mosseae) at three inorganic-P levels (50, 75 & 100 % of soil-test based P-dose) and two irrigation-regimes (40 & 80 % AWC). AMF-inoculation significantly enhanced the system-productivity (∼11 %), bio-energy output (∼8 %) and SOC-storage over non-AMF plots in OPCS. Carbon-input use followed the trend of water>diesel>fertilizers> FYM > herbicides> pesticides>AMF in OPCS. AMF-inoculation significantly reduced the carbon-footprints (0.466 kg CO2-e kg-1) by ∼10.2 % over non-AMF plots. Soil-test based 100 % P-dose significantly enhanced the system-productivity (6.3-15.6 %) and bio-energy output (4.7-12.6 %) with lesser carbon-footprints (5.3-15 %) over 50 and 75 % P-dose. Irrigation at 80 % AWC enhanced system-productivity (∼4.1 %), however at 40 % AWC reduced carbon-footprints by ∼11.7 % besides saving irrigation-water by ∼24 % (150 mm ha-1/year) in OPCS. Hence, farmers must necessarily use AMF-inoculation coupled with soil-test based P-fertilization (75-100 %) while preserving a balance in irrigation water-use at 40-80 % AWC depending upon water-availability for higher crop- and water-productivity besides lesser energy and carbon-footprints in OPCS in Himalayan acid Alfisol.

Triple-zero tillage and system intensification lead to enhanced productivity, micronutrient biofortification and moisture-stress tolerance ability in chickpea in a pearlmillet-chickpea cropping system of semi-arid climate

Pearlmillet-chickpea cropping system (PCCS) is emerging as an important sequence in semi-arid regions of south-Asia owing to less water-requirement. However, chickpea (dry-season crop) faces comparatively acute soil moisture-deficit over pearlmillet (wet-season crop), limiting overall sustainability of PCCS. Hence, moisture-management (specifically in chickpea) and system intensification is highly essential for sustaining the PCCS in holistic manner. Since, conservation agriculture (CA) has emerged is an important climate-smart strategy to combat moisture-stress alongwith other production-vulnerabilities. Hence, current study comprised of three tillage systems in main-plots viz., Complete-CA with residue retention (CAc), Partial-CA without residue-retention (CAp), and Conventional-tillage (ConvTill) under three cropping systems in sub-plots viz., conventionally grown pearlmillet-chickpea cropping system (PCCS) alongwith two intensified systems i.e. pearlmillet-chickpea-fodder pearlmillet cropping system (PCFCS) and pearlmillet-chickpea-mungbean cropping system (PCMCS) in split-plot design. The investigation outcomes mainly focused on chickpea (dry-season crop) revealed that, on an average, there was a significant increase in chickpea grain yield under CAc to the tune of 27, 23.5 and 28.5% under PCCS, PCFCS and PCMCS, respectively over ConvTill. NPK uptake and micronutrient (Fe and Zn) biofortification in chickpea grains were again significantly higher under triple zero-tilled CAc plots with residue-retention; which was followed by triple zero-tilled CAp plots without residue-retention and the ConvTill plots. Likewise, CAc under PCMCS led to an increase in relative leaf water (RLW) content in chickpea by ~ 20.8% over ConvTill under PCCS, hence, ameliorating the moisture-stress effects. Interestingly, CA-management and system-intensification significantly enhanced the plant biochemical properties in chickpea viz., super-oxide dismutase, ascorbate peroxidase, catalase and glutathione reductase; thus, indicating their prime role in inducing moisture-stress tolerance ability in moisture-starved chickpea. Triple zero-tilled CAc plots also reduced the N2O fluxes in chickpea but with slightly higher CO2 emissions, however, curtailed the net GHG-emissions. Triple zero-tilled cropping systems (PCFCS and PCMCS) both under CAc and Cap led to a significant improvement in soil microbial population and soil enzymes activities (alkaline phosphatase, fluorescein diacetate, dehydrogenase). Overall, the PCCS system-intensification with mungbean (PCMCS) alongwith triple zero-tillage with residue-retention (CAc) may amply enhance the productivity, micronutrient biofortification and moisture-stress tolerance ability in chickpea besides propelling the ecological benefits under semi-arid agro-ecologies. However, the farmers should preserve a balance while adopting CAc or CAp where livestock equally competes for quality fodder.

Impact of biofertilisers on iron homeostasis and grain quality in the rice variety Uma under Elevated CO2

The diminishing nutritional quality of rice with increasing concentrations of atmospheric CO₂ is currently a major global concern. The present study was designed with the objective of assessing the impact of biofertilisers on grain quality and iron homeostasis in rice under elevated CO₂. A completely randomised design with four treatments ([KAU, POP (control), POP+Azolla, POP+PGPR, and POP+AMF]), each replicated three times under ambient and elevated CO₂ conditions, was followed. The analysed data revealed that yield, grain quality, and iron uptake and translocation were modified in an unfavourable manner under elevated CO₂, which was reflected in the lower quality and iron content of the grains. The response of iron homeostasis in the experimental plants to the application of biofertilisers, especially plant-growth-promoting rhizobacteria (PGPR), under elevated CO₂ strongly suggests the possibility of utilising them for designing iron management strategies for achieving higher quality in rice.

Elucidating the impact of boron fertilization on soil physico-chemical and biological entities under cauliflower-cowpea-okra cropping system in an Eastern Himalayan acidic Inceptisol

Information on the role of boron (B) on soil physico-chemical and biological entities is scarce, and the precise mechanism in soil is still obscure. Present field investigation aimed to assessing the implication of direct and residual effect of graded levels of applied-B on soil biological entities and its concomitant impact on crop productivity. The treatments comprised of five graded levels of B with four replications. To assess the direct effect of B-fertilization, cauliflower was grown as a test crop wherein, B-fertilization was done every year. For assessment of succeeding residual effects of B-fertilization, cowpea and okra were grown as test crops and, B-fertilization was phased out in both crops. The 100% recommended dose of NPK (RDF) along with FYM was uniformly applied to all crops under CCOCS. Results indicated that the direct effect of B had the edge over residual effect of B in affecting soil physico-chemical and biological entities under CCOCS. Amongst the graded levels of B, application of the highest B level (2 kg ha^–1) was most prominent in augmenting microbiological pools in soil at different crop growth stages. The order of B treatments in respect of MBC, MBN, and soil respiration at different crop growth stages was 2.0 kg B ha^–1 > 1.5 kg B ha^–1 > 1.0 kg B ha^–1 > 0.5 kg B ha^–1 > 0 kg B ha^–1, respectively. Moreover, maximum recoveries of potentially mineralizable-C (PMC) and potentially mineralizable-N (PMN) were noticed under 2 kg B ha^–1. Analogous trend was recorded in soil microbial populations at different crop growth stages. Similarly, escalating B levels up to 2 kg B ha^–1 exhibited significantly greater soil enzymatic activities viz., arylsulphatase (AS), dehydrogenase (DH), fluorescein diacetate (FDA) and phosphomonoesterase (PMA), except urease enzyme (UE) which showed an antagonistic effect of applied-B in soil. Greater geometric mean enzyme activity (GMEA) and soil functional diversity index were recorded under 2 kg B ha^–1 in CCOCS, at all crop growth stages over control. The inclusive results indicated that different soil physico-chemical and biological properties CCOCS can be invariably improved by the application of graded levels of B up to 2 kg B ha^–1 in an acid Inceptisol.

Integrated management enhances crop physiology and final yield in maize intercropped with blackgram in semiarid South Asia

Photosynthesis, crop health and dry matter partitioning are among the most important factors influencing crop productivity and quality. Identifying variation in these parameters may help discover the plausible causes for crop productivity differences under various management practices and cropping systems. Thus, a 2-year (2019-2020) study was undertaken to investigate how far the integrated crop management (ICM) modules and cropping systems affect maize physiology, photosynthetic characteristics, crop vigour and productivity in a holistic manner. The treatments included nine main-plot ICM treatments [ICM₁ to ICM₄ - conventional tillage (CT)-based; ICM₅ to ICM₈ - conservation agriculture (CA)-based; ICM₉ - organic agriculture (OA)-based] and two cropping systems, viz., maize-wheat and maize + blackgram-wheat in subplots. The CA-based ICM module, ICM₇ resulted in significant (p < 0.05) improvements in the physiological parameters, viz., photosynthetic rate (42.56 μ mol CO₂ m^-2 sec^-1), transpiration rate (9.88 m mol H₂O m^-2 sec^-1) and net assimilation rate (NAR) (2.81 mg cm^-2 day^-1), crop vigour [NDVI (0.78), chlorophyll content (53.0)], dry matter partitioning toward grain and finally increased maize crop productivity (6.66 t ha^-1) by 13.4-14.2 and 27.3-28.0% over CT- and OA-based modules. For maize equivalent grain yield (MEGY), the ICM modules followed the trend as ICM₇ > ICM₈ > ICM₅ > ICM₆ > ICM₃ > ICM₄ > ICM₁ > ICM₂ > ICM₉. Multivariate and PCA analyses also revealed a positive correlation between physiological parameters, barring NAR and both grain and stover yields. Our study proposes an explanation for improved productivity of blackgram-intercropped maize under CA-based ICM management through significant improvements in physiological and photosynthetic characteristics and crop vigour. Overall, the CA-based ICM module ICM₇ coupled with the maize + blackgram intercropping system could be suggested for wider adoption to enhance the maize production in semiarid regions of India and similar agroecologies across the globe.

Double zero-tillage and foliar-P nutrition coupled with bio-inoculants enhance physiological photosynthetic characteristics and resilience to nutritional and environmental stresses in maize-wheat rotation

Conventionally tilled maize-wheat cropping system (MWCS) is an emerging cereal production system in semi-arid region of south-Asia. This system involves excessive tillage operations that result in numerous resource- and production-vulnerabilities besides impeding environmental-stresses. Likewise, phosphorus is a vital nutrient that limits crop growth and development. It's a matter of great concern when ∼80% of Indian soils are low to medium in available-P due to its sparing solubility, resulting in crop stress and low yields. Hence, crop productivity, photosynthetic parameters and resilience to nutritional and environmental stresses were assessed in a MWCS using four crop-establishment and tillage management (CETM) practices [FBCT-FBCT (Flat bed-conventional tillage both in maize and wheat); RBCT-RBZT (Raised bed-CT in maize and raised bed-zero tillage in wheat); FBZT-FBZT (FBZT both in maize and wheat); PRBZT-PRBZT (Permanent raised bed-ZT both in maize and wheat)], and five P-fertilization practices [P₁₀₀ (100% soil applied-P); P₅₀+2FSP (50% soil applied-P + 2 foliar-sprays of P through 2% DAP both in maize and wheat); P₅₀+PSB+AM-fungi; P₅₀+PSB+AMF+2FSP; and P₀ (100% NK with no-P)] in split-plot design replicated-thrice. The results indicated that double zero-tilled PRBZT-PRBZT system significantly enhanced the grain yield (6.1; 5.4 t ha^-1), net photosynthetic rate (Pn) (41.68; 23.33 μ mol CO₂ m^-2 s^-1), stomatal conductance (SC) (0.44; 0.26 mol H₂O m^-2 s^-1), relative water content (RWC) (83.3; 77.8%), and radiation-use efficiency (RUE) (2.9; 2.36 g MJ^-1) by 12.8-15.8 and 8.5-44.4% in maize and wheat crops, respectively over conventional tilled FBCT-FBCT. P₅₀+PSB+AMF+2FSP conjugating soil applied-P, microbial-inoculants and foliar-P, had significantly higher Pn, SC, RUE and RWC over P₁₀₀ besides saving ∼34.7% fertilizer-P under MWCS. P₅₀+PSB+AMF+2FSP practice also had higher NDVI, PAR, transpiration efficiency and PHI over P₁₀₀. Whereas lower stomatal limitation index (Ls) was observed under PRBZT-PRBZT system as compared to the conventional FBCT-FBCT system indicating that P is the limiting factor but not stomata. Hence, optimum P supply through foliar P-fertilization along with other sources resulted in higher grain yield by 21.4% over control. Overall, double zero-tilled PRBZT-PRBZT with crop residue retention at 6 t/ha per year, as well as P₅₀+PSB+AMF+2FSP in MWCS, may prove beneficial in enhancing the crop productivity and, thereby, bolstering food security in semi-arid south-Asia region.

Microbes-mediated integrated nutrient management for improved rhizo-modulation, pigeonpea productivity, and soil bio-fertility in a semi-arid agro-ecology

Excessive dependence on chemical fertilizers and ignorance to organic and microbial inputs under intensive cropping systems are the basic components of contemporary agriculture, which evolves several sustainability issues, such as degraded soil health and sub-optimal crop productivity. This scenario urges for integrated nutrient management approaches, such as microbes-mediated integrated plant nutrition for curtailing the high doses as chemical fertilizers. Rationally, experiment has been conducted in pigeonpea at ICAR-IARI, New Delhi, with the aim of identifying the appropriate nutrient management technique involving microbial and organic nutrient sources for improved rhizo-modulation, crop productivity, and soil bio-fertility. The randomized block-designed experiment consisted nine treatments viz. Control, Recommended dose of fertilizers (RDF), RDF+ Microbial inoculants (MI), Vermicompost (VC), Farm Yard Manure (FYM), Leaf Compost (LC), VC + MI, FYM + MI, and LC + MI. Rhizobium spp., Pseudomonas spp., Bacillus spp., and Frateuria aurantia were used as seed-inoculating microbes. The results indicated the significant response of integration following the trend VC + MI > FYM + MI > LC + MI > RDF + MI for various plant shoot-root growth attributes and soil microbial and enzymatic properties. FYM + MI significantly improved the water-stable aggregates (22%), mean weight diameter (1.13 mm), and geometric mean diameter (0.93 mm), soil organic carbon (SOC), SOC stock, and SOC sequestration. The chemical properties viz. available N, P, and K were significantly improved with VC + MI. The study summarizes that FYM + MI could result in better soil physico-chemical and biological properties and shoot-root development; however; VC + MI could improve available nutrients in the soil and may enhance the growth of pigeonpea more effectively. The outcomes of the study are postulated as a viable and alternative solution for excessive chemical fertilizer-based nutrient management and would also promote the microbial consortia and organic manures-based agro-industries. This would add to the goal of sustainable agricultural development by producing quality crop produce, maintaining agro-biodiversity and making the soils fertile and healthy that would be a “gift to the society.”