Accelerated erosion removes fertile top soil along with nutrients through runoff and sediments, eventually affecting crop productivity and land degradation. However, scanty information is available on soil and nutrient losses under different crop covers in a vertisol of Central India. Thus, a field experiment was conducted for 4 years (2010–2013) to study the effect of different crop cover combinations on soil and nutrient losses through runoff in a vertisol.
Materials and methods
Very limited information is available on runoff, soil, and nutrient losses under different vegetative covers in a rainfed vertisol. Thus, the hypothesis of the study was to evaluate if different crop cover combinations would have greater impact on reducing soil and nutrient losses compared to control plots in a vertisol.
This experiment consisted of seven treatment combinations of crop covers namely soybean (Glycine max) (CC1), maize (Zea mays) (CC2), pigeon pea (Cajanus cajan) (CC3), soybean (Glycine max)?+?maize (Zea mays) ??1:1 (CC4), soybean (Glycine ma x))?+?pigeon pea (Cajanus cajan) ?2:1 (CC5), maize (Zea mays)?+?pigeon pea (Cajanus cajan) ??1:1 (CC6), and cultivated fallow (CC7). The plot size was 10?×?5 m with 1% slope, and runoff and soil loss were measured using multi-slot devisor. All treatments were arranged in a randomized block design with three replications.
Results and discussion
Results demonstrated that the runoff and soil loss were significantly (p?<?0.05) higher (289 mm and 3.92 Mg ha?1) under cultivated fallow than those in cropped plots. Among various crop covers, sole pigeon pea (CC3) recorded significantly higher runoff and soil loss (257 mm and 3.16 Mg ha?1) followed by that under sole maize (CC2) (235 mm and 2.85 Mg ha?1) and the intercrops were in the order of maize?+?pigeon pea (211 mm and 2.47 Mg ha?1) followed by soybean?+?maize (202 mm and 2.38 Mg ha?1), and soybean?+?pigeon pea (195 mm and 2.15 Mg ha?1). The lowest runoff and soil loss were recorded under soybean sole crop (194 mm and 2.27 Mg ha?1). The data on nutrient losses indicated that the highest losses of soil organic carbon (SOC) (25.83 kg ha?1), total nitrogen (N), phosphorus (P), and potassium (K) (7.76, 0.96, 32.5 kg ha?1) were recorded in cultivated fallow (CC7) as compared to those from sole and intercrop treatments. However, sole soybean and its intercrops recorded the minimum losses of SOC and total N, P, and K, whereas the maximum losses of nutrients were recorded under pigeon pea (CC3). The system productivity in terms of soybean grain equivalent yield (SGEY) was higher (p?<?0.05) from maize?+?pigeon pea (3358 kg ha?1) followed by that for soybean?+?pigeon pea (2191 kg ha?1) as compared to sole soybean. Therefore, maize?+?pigeon pea (1:1) intercropping is the promising option in reducing runoff, soil-nutrient losses, and enhancing crop productivity in the hot sub-humid eco-region.
Conclusions
Study results highlight the need for maintenance of suitable vegetative cover as of great significance to diffusing the erosive energy of heavy rains and also safe guarding the soil resource from degradation by water erosion in vertisols.
Comparisons were made of the accumulation of cadmium, copper, manganese, lead, and zinc in Plagiothecium denticulatum, Bryum argenteum and Sphagnum sp. in Shillong, Meghalaya State, Northeastern India. Samples of P. denticulatum and B. argenteum were collected inside Shillong city (urban) and its immediately adjacent outskirts (suburban), while Sphagnum sp. was collected from a suburban site only. Lead and copper levels were higher in P. denticulatum, while Sphagnum sp. accumulated higher amounts of zinc, manganese, and cadmium. An urban-suburban gradient was evident for lead and zinc in P. denticulatum, and for cadmium in B. argenteum, while a reverse trend could be discerned for manganese in P. denticulatum. Besides vehicles and minor industries, quarry dust was likely to be an important source of manganese, copper, and zinc. 相似文献
In a greenhouse experiment, the nutrients NPK, NPK + lime, K, and Mn were applied to an iron-toxic soil (Typic Haplastulf). Soil pH and dry matter production were increased and Eh and available Fe in the soil were decreased. Though liming the soil decreased available Fe and Mn and increased pH to the greatest extent, the highest dry matter production was obtained with NPK application. NPK + lime produced a smaller yield than NPK without lime. Though the application of K or Mn alone produced much less dry matter than NPK or NPK + lime, no symptoms of Fe toxicity were observed. We conclude that Fe toxicity can be reduced with a balanced use of fertilizers (NPK or NPK + lime) and its occurrence was mostly due to nutrient stress. 相似文献
Although chemical and some soil physical properties have been studied under different land uses of the Lesser Himalayas of India, very limited information is available on soil biochemical properties. Hence we investigated phosphorus (P) fractions [total P (TP), inorganic P (Pi), organic P (Po), available P, microbial biomass P (MBP)], enzyme activities [dehydrogenase, phosphatases, phytase], phosphate solubilizing bacteria (PSB) and fungi (PSF), and their correlations of acid soils (0–15 and 15–30 cm depths) under different land uses (viz, organic farming, maize–wheat, apple orchard, undisturbed oak forest and uncultivated land of the Indian Himalayas). All land use systems differed significantly for the P fractions, except TP. The highest values for TP, Pi, available P and MBP were found in soils under oak forest and lowest in uncultivated land. However, Po content was highest in apple orchard. The organic farming (organic manures field under garden pea-french bean cropping system for > 10 years) maintained highest activities of dehydrogenase, acid phosphatase and alkaline phosphatase. The highest phytase activity and highest numbers of PSB (99 × 103 g?1 soil) and PSF (30 × 103 g?1 soil) were observed in the rhizosphere soils of oak forest. Significant relationships between soil P fractions and enzyme activities, except alkaline phosphatase, were recorded in surface soil layer. PSB and PSF population were also correlated significantly with P fractions and enzyme activities. This would lead us to understand the level of degradation of P pools due to cultivation over forest system and the suitable management practices needed for soil quality restoration. 相似文献
Nano-sized formulations of micronutrient iron (Fe) were found to substantially alter the growth and metabolism of maize plants. Plants fertilized with the optimal recommended dose of Fe in the nano-form (54 μM) registered an enhancement in morphological features, viz. plant height, biomass (shoot and root), and diminution in antioxidant enzyme activities than the plants fertilized with the sub-optimal dose of Fe in the macroform (salts). However, half of the recommended dosage of Fe (27 μM) in the nano-form positively influenced leaf area and proline content of plants too. This indicated that there is a possibility of reducing the dose of Fe supplement for plants in the nano-form to increase the nutrient use efficiency in a major cereal crop like maize. This may open a new era in plant nutrient management with a scope for improvement in nutrient use efficiency using nano-nutrient formulations. 相似文献
The N loss from Vertisols was estimated by measuring the loss of 15N-labelled urea N under conditions that promote NH3 volatilization. Urea granules were placed on the top of 150-mm deep soil columns (Vertisols) collected from three sites with a range in pH, electrical conductivity, and cation exchange capacity. There were two contrasting moisture treatments, one near field capacity (wet) and another with intermittent wetting of the soil surface before allowing the columns to dry (moist-dry). The results indicated that losses were influenced markedly by pH and moisture treatment, being 29.5, 33.5, and 33% from the wet soils and 37, 42, and 40.5% from the moistdry soils with pH values of 7.7, 8.2, and 9.3, respectively. These observations clearly indicate that broadcasting of urea on the surface of Vertisols may cause substantial N losses. 相似文献
Summary An attempt has been made to estimate quantitatively the amount of N fixed by legume and transferred to the cereal in association in intercropping systems of wheat (Triticum aestivum L.) — gram (Cicer arietinum L.) and maize (Zea mays L.) —cowpea (Vigna unguiculate L.) by labelling soil and fertilizer nitrogen with 15N. The intercropped legumes have been found to fix significantly higher amounts of N as compared with legumes in sole cropping if the intercropped cereal-legume received the same dose of fertilizer N as the sole cereal crop. But when half of the dose of the fertilizer N applied to sole cereal crop was received by intercropped plants, the amount of N fixed by legumes in association with cereals was significantly less than that fixed by sole legumes. Under field conditions 28% of the total N uptake by maize (21.2 kg N ha–1) was of atmospheric origin and was obtained by transfer of fixed N by cowpea grown in association with maize. Under greenhouse conditions gram and summer and monsoon season cowpea have been found to contribute 14%–20%, 16% and 32% of the total N uptake by associated wheat and summer and monsoon maize crops, respectively. Inoculation of cowpea seeds with Rhizobium increased both the amount of N fixed by cowpea and transferred to maize in intercropping system. 相似文献
A meta-analysis of data obtained from previous studies was conducted to understand the responses of foliage supplementation on intakes of basal DM (BDMI) and total DM (TDMI), and daily gain (ADG). Thirty-four published studies containing 223 treatments and 1127 sheep met criteria for inclusion in the meta-analysis. Major predictive variables considered were percentages of foliages in diet (SD), CP in foliages (PS), NDF in foliages (FS), NDF in forages (FB), CP in basal roughages (PB), CP in diet (PD) and foliage CP intake (SPI). TDMI (g/d) increased quadratically (P < 0.001) with increasing PS, FS, SPI (R2 = 0.66), PB, SD (R2 = 0.58) and PD (R2 = 0.73). The maximal response of TDMI were 778 g/d at 42% of SD, 894 g/d at 19.8% PD, 893 g/d at 148 g/d SPI and 749 g/d at 26.4% PS (P < 0.001; R2 = 0.58, 0.73, 0.66, and 0.37, respectively). BDMI increased quadratically with increasing SD, PD and PB, but decreased quadratically (P < 0.001) with increasing PS (P < 0.001; R2 = 0.07). The breakpoint of BDMI was 570 g/d at 6.58% of PD in the diet (P < 0.001, R2 = 0.28). Overall, BDMI responded at very low level of SD in the diet, peaking at 7.6% SD with BDMI of 572 g/d (P < 0.001, R2 = 0.72). However, when PB was less than 3%, the maximal BDMI was 489 g/d at foliage levels of 25.7%. When PB was between 3 and 6%, maximal BDMI was at 13% of foliage in the diet and the basal forage intake of 597 g/d; whereas, BDMI decreased linearly with SD when PB was greater than 6%. BDMI (g/d) decreased quadratically when foliage CP percentages were lesser than 10%, but increased quadratically with PS when foliage CP percentages were greater than 10%. ADG responded positively and quadratically to PS, SPI, SD, PD and TDMI (g/d) and the relationships were moderate to high. However, ADG (g/d) decreased linearly with increasing FS (P < 0.001, R2 = 0.35). The maximal ADG was 42 g/d at 43% of SD, 41 g/d at 9.4% PD, 42 g/d at 53 g/d SPI, 35 g/d at 25% PS and 46 g/d at TDMI of 889 g/d (P < 0.001; R2 = 0.74, 0.84, 0.74, 0.29 and 0.74, respectively). It is concluded that the interactions of quality and quantity of foliage supplements and quality of basal forages affect intakes of basal and total DM, and growth in sheep. 相似文献