Microsoft Word - 1murphy.docx


CHEMICAL ENGINEERINGTRANSACTIONS 
 

VOL. 58, 2017 

A publication of 

 

The Italian Association 
of Chemical Engineering 
Online at www.aidic.it/cet 

Guest Editors:Remigio Berruto, Pietro Catania, Mariangela Vallone
Copyright © 2017, AIDIC Servizi S.r.l. 
ISBN978-88-95608-52-5; ISSN 2283-9216 

Organic Matter, Irrigation and Soil Mulching in the Nutritional 
Status and Production of Okra  

Lúcia H. G. Chaves*a, Evandro F. Mesquitab, Daniel S. Ferreirab, Sebastião O. M. 
Mesquita Sobrinhob  
a 
Department of Agricultural Engineering of Federal University of Campina Grande. Avenue Aprigio Veloso, 882, CEP 

58429140 Campina Grande, Paraiba State, Brazil 
b 

Department of Agrarian and Exact of State University of Paraíba. Baraúnas Street, 351, CEP 58429-500 Campina Grande, 
Paraiba State, Brazil 
lhgarofalo@hotmail.com  

The Brazilian semiarid region is characterized by dry and hot climate, with low rainfall and poorly distributed 
over time. In the soils of this region, due to the high temperatures, organic matter (OM) decomposes quickly, 
resulting in low reserve levels. To improve fertility and reduce the evaporation of these soils, cattle manure 
has been applied as organic fertilizer and vegetal wastes as mulch, respectively. Based on this, this study 
aimed at evaluating the effect of elevation of the OM content, irrigation and soil mulching in leaf micronutrient 
okra. The experiment was carried out at the Agroecology Sector of Paraíba State University, Brazil, during the 
period from September 2015 to February 2016. The treatments were distributed in randomized blocks in a 
factorial design 5 x 2 x 2, referring to the following treatments: five rates of cattle manure in sufficient rates to 
raise the content of OM in the soil from 1.80 (value existent in the soil) to 2.8; 3.8; 4.8 and 5.8%, two water 
depths (50 and 100%) of crop evapotranspiration (ETc) and soil with and without mulching with plant parsley. 
At the beginning of flowering (45 days after sowing (DAS)), leaf D was collected from four plants of each 
treatment to determine the boron (B), copper (Cu) and zinc (Zn) levels to evaluate the nutritional status of the 
crop.Harvesting started at 64 DAS up until 150 DAS; in this period the average weight of green fruits per plant 
was obtained (g). The interaction of OM with water slides significantly influenced the Cu contents in okra 
leaves. However, the interaction of the three factors significantly influenced only B, Zn and fruit weight. The 
management used in this study improved the nutritional status of the okra plant and increase its production.  

1. Introduction 

Okra, whose scientific name is Abelmoschus esculentus L. of the Malvaceae family, originated in tropical 
Africa was introduced in Brazil with the slave trade and is currently cultivated in several tropical, subtropical 
and temperate regions of the world. It is a vegetable of relatively low cost of production, possessing a fast 
cycle, practically no fat, high in fiber, and have several valuable nutrients, including about 30% of the 
recommended levels of vitamin C (16 to 29 mg), 10 to 20% of folate (46 to 88 g) and about 5% of vitamin A; 
also okra has in its composition minerals such as calcium, fiber and protein.  
To enrich the soil in relation to organic matter it is important to apply organic fertilizer to the soil, for example, 
cattle manure. This fertilizer improves physical and chemical characteristics of the soils releasing the macro 
and micronutrients for soils through mineralization. For the mineralization of cattle manure and an efficient 
nutrient absorption by the plants, it is necessary for the soil humidity to be in sufficient quantity (Danso et al., 
2015). In the northeastern region of Brazil, where low pluviometry is associated with constant irregularity of 
rainfall, it is necessary to provide water to the culture through the use of irrigation techniques, to increase 
productivity by optimizing the use of water resources (Barbosa et al., 2015). According to Nana et al. (2014) 
the main constraint in cultivation of okra is the lack of rainfall which limits severely production. In this region, 
because of the climatic type, ie, semiarid climate, in addition to irrigation, the use of mulch in the soil surface is 
a crop management technique that keep the water content of the soil and / or reduces hydric loss through 
evaporation as Wang and Wang (2016);  the efficiency of this technique was observed by Teofilo et al. (2012). 

                               
 
 

 

 
   

                                                  
DOI: 10.3303/CET1758118

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Please cite this article as: Chaves L., Mesquita E., Ferreira D., Mesquita Sobrinho S., 2017, Organic matter, irrigation and soil mulching in the 
nutritional status and production of okra, Chemical Engineering Transactions, 58, 703-708  DOI: 10.3303/CET1758118 

703



Thus, the main objective of this study was at evaluating the effect of increasing the organic matter content, 
irrigation and soil mulching in leaf micronutrient of okra and fruit weight. 

2. Materials and Methods 

The experiment was carried out at the Agroecology Sector of Paraíba State University, Campus IV, Catolé do 
Rocha, Paraíba State, Brazil (6˚20’38”S, 37˚44’48’’W and 275 m above mean sea level) during the period from 
September/2015 to February/2016. The total rainfall of the region was 230 mm, out of which 85% falls in 
between January and February. The climate in the region is the BSw’h’ type, according to Kõppen 
classification, characterized as hot semiarid with two distinct seasons, a rainy one with irregular precipitation 
and another without precipitation. The data observed at meteorological station indicates that the average, 
maximum and minimum air temperature was 28 oC, 35 oC and 23 oC, respectively. The average relative 
humidity in the dry months is less than 50%. The experimental soil according to Embrapa (2013) was 
classified as Eutrophic Fluvic Neosoil (661 g kg-1 sand,  213 g kg-1  silt and 126 g kg-1 clay). The chemical 
properties of the soil were pH 7.0, cation exchange capacity 8.08 cmolc kg

-1, organic matter 18 g kg-1, 
phosphorous and potassium as 31 and 297 mg kg-1 soil, respectively,  sodium, calcium, magnesium, 
aluminum and hydrogen + aluminum as 0.30; 4.63; 2.39; 0.0 and 0.0, cmolc kg

-1, respectively. The okra 
(Abelmoschus esculentus (L.) Moench) cultivar grown under the experiment was ‘Santa Cruz 47’. The 
treatments were distributed in randomized blocks in a factorial design 5 x 2 x 2, referring to the following 
treatments: five rates of cattle manure C/N ratio of 18:1, two water depths (50 and 100%) of crop 
evapotranspiration (ETc mm/day) and soil with and without mulching with plant debris of crushed dried parsley 
(Ipomoea asarifolia) in a layer 5 cm thick, with four replications, totaling 80 plots. The pits were opened in the 
dimensions of 30 cm x 30 cm x 30 cm, with spacing of 1 m between rows and 0.4 m between plants and 
prepared with soil material from the first 30 cm, with cattle manure C/N ratio 18:1 (Table 1), in sufficient rates 
to raise the content of organic matter in the soil from 1.80 (value existent in the soil) to 2.8; 3.8; 4.8 and 5.8% 
(0.0; 1081; 2162; 3243 and 4324 g/pit of cattle manure, respectively). The irrigation of the plants was carried 
out daily by the method of localized irrigation, adopting the drip system, according to the crop 
evapotranspiration ETc (mm day-1). The calculation was based on the reference evapotranspiration (Eto, 
mm/day), estimated by the class A tank and corrected by the Kc of culture according to the development stage 
of the plant. The irrigation system produces a wet strip with a single drip tape per plant. The sowing was done 
in the second week of September 2015, with five seeds of okra (Abelmoschus esculentus (L.) Moench) 
cultivar Santa Cruz 47, per pit. The thinning was performed when the plants had three true leaves in the first 
week of October 2015, keeping only the strongest plant per pit.The differentiation of the water slides was done 
at 15 days after sowing (DAS), such as the application of mulch with vegetable detritus (Ipomoea asarifolia), 5 
cm thick in the crown projection (30 x 30 cm). The mean total consumption was 425 mm and 212 mm for the 
100% and 50% ETc slides of the culture, respectively. At the beginning of flowering (45 DAS), leaf D (fourth 
leaf from the apex of the plant, that is, the intermediate leaf of the plant with maximum photosynthesis) was 
collected from four plants of each treatment to determine the boron (B), copper (Cu) and zinc (Zn) levels to 
evaluate the nutritional status of the crop (Filgueira, 2013), according to Malavolta et al. (1997).Harvesting 
started at 64 DAS, being done twice a week up to 150 DAS; in this period the average weight of green fruits 
per plant were obtained, expressed in g/plant. The results were submitted to variance analysis by the "F" test 
and polynomial regression, using the statistical software Sisvar 5.0 (Ferreira, 2011). 

3. Results and discussion 

The interaction between water depths, levels of organic matter and soil mulch is significant, except for the 
foliar levels of Cu and Zn (Table 1).  
The absorption of nutrients by plants is dependent upon a number of factors, such as the availability of these 
elements in the soil and appropriate humidity conditions.  
Regardless of the soil with and without mulch, higher foliar levels of boron were observed in plants irrigated 
with the highest water level (100% ETc) (Figure 1).  
The accumulation of boron in okra leaves cultivated in area with mulching was adjusted to the increasing 
linear model with increments of 1.6 and 1.4 mg kg-1 for each unit increase of the organic input (Figure 1A). 
The highest boron concentrations were 52.1 and 46.5 g kg-1 in plants with water depths of 100 and 50% of 
crop evapotranspiration (ETc). It is observed that the difference between these boron foliar concentrations 
was higher than 10% due to the reduction of the water supply from 100 to 50% ETc. Boron data were adjusted 
to the quadratic polynomial model with maxima of 50.30 and 47.57 mg kg-1, respectively, for the cultivated 
plants without mulching, irrigated with 100% and 50% ETc (Figure 1B). The increase of organic matter in the 
soil provided an increase in B content in the dry matter of okra leaves; according to researchers, soil organic 

704



matter is the main source of B for plants. The plants irrigated with 100% ETc showed higher levels of B in the 
dry matter in leaves of okra compared to those irrigated with 50% ETc, because the plants under water stress 
close their stomata to reduce water losses through evapotranspiration. With this, the B-root contact occurs 
basically because of the mass flow that is affected by the transpiratory rate of the plant, including the okra. 
 
Table 1: Summary of variance analysis related to the variables boron (B), copper (Cu), zinc (Zn) in leaves of 
okra variety Santa Cruz and the weight of fruit per plant (WF) when subjected to levels of organic matter in the 
soil, water depths, with and without soil mulch. 
 

Source of 
variation 

DF Square mean 
B Cu Zn WF 

Block 3 ns ns ns ns 
OM  4 ** ** ** ** 
SM 1 ns * ** ns 
Depths (D) 1 ** ** ** ** 
OM x SM 4 ns ns ** * 
OM x D 4 ns * ns ** 
SM x D 1 ns ns ns ns 
OM x SM x D 4 ** ns ns ** 
Residue 57 3.40 2.36 5.38 20,069.07 
CV (%)  3.99 15.03 5.81 16.20 
   g kg-1  g/plant 
General 
average 

 46.15 10.23 39.92 874.43 

                                 Significant at 5% (*) and 1% (**) of probability by F test; (ns) not significant; 
                                 DF= degree of freedom; CV%= Coefficient of variation; OM= organic matter; 
                                 SM= soil mulching. 
 

y ̂(-)= 40.21 + 2.05x
R2= 0.94 y ̂(...)= 38.96 +1.3x 

R2= 0.95

20

30

40

50

60

B
 (

m
g
 k

g
-1

)

100% ETc 50% ETc

 

y ̂(-) =41,02 + 3,05**x - 0,25**x2
R2= 0,94 y ̂(...)=23,66 + 9,11**x - 0,86**x2

R2= 0,99

20

30

40

50

60

1.8 2.8 3.8 4.8 5.8

B
 (
m

g
 k

g
-1

)

Level of soil organic matter  (%)  

Figure 1: Boron content in okra leaves depending on the levels of organic matter, irrigation with 100% (___) 
and 50% ETc (---), in a soil with (A) and without mulch (B) 

A 

B 

705



Copper content in the dry matter of the okra leaves was influenced by the factors isolated organic matter, 
irrigation slides and mulching and by the interaction organic matter x irrigation slides (Table 1). Cu content in 
the dry matter of the okra leaves cultivated in mulched areas, adjusted to the quadratic polynomial model and 
linear model in the plants irrigated with 100% and 50% ETc, respectively, reaching the maximum values of 
12.91 and 10. 3 mg kg-1 for the estimated levels of 3.9 and 5.8% of organic matter (Figure 2A). Cu contents in 
the okra leaves cultivated in the areas without mulch, adjusted to the quadratic polynomial model in the plants 
irrigated with 100%, reached the maximum value of 12.19 mg kg-1 referring to the estimated level of 3.7 
organic matter (Figure 2B). 
 

y ̂(-)=  - 0.58 + 6.93**x - 0.89**x2
R2= 0.77

y ̂(..)=5.37 + 0.85**x  
R2= 0.78

0

4

8

12

16

C
u

 (
m

g
 k

g
-1

)

100% ETc 50% ETc

 

y ̂(-)=5.99 + 3.38**x - 0.46**x2
R2= 0.45

y ̂(..)= 10
0

4

8

12

16

1.8 2.8 3.8 4.8 5.8

C
u

 (
m

g
 k

g
-1

)

Level of soil organic matter  (%)  

Figure 2: Copper content in okra leaves depending on the levels of organic matter, irrigation with 100% (___) 
and 50% ETc (---), in a soil with (A) and without mulch (B) 

The Zn content in the dry matter of the okra leaves was influenced by the factors isolated organic matter, 
irrigation slides and mulching and by the interaction of organic matter and mulch (Table 1). 
The addition of organic matter promoted an increase in Zn leaf content in the plants up to the maximum levels 
of 47.48 and 40.70 mg kg-1 (Figure 3A) and 45.72 and 39.78 mg kg-1 (Figure 3 B) for the levels of 4.2 and 
4.4% of MOS and 3.9 and 3.7% MOS for the plants irrigated with the 100% and 50% ETc slides, with and 
without mulching, respectively.  
The Zn contents in okra leaves were higher in plants cultivated without water stress in comparison to those 
cultivated under water deficit. These results indicate that the reduction of the irrigation depth from 100 to 50% 
of ETc caused a decline in zinc leaf accumulation of 14.28% and 12.99%, probably because the Zn-root 
contact is by diffusion, which is influenced by the concentration gradient close to the root. 
The weight of okra fruits per plant was influenced by the isolated factors organic matter and irrigation slides 
and by the interaction organic matter x irrigation sheets x mulching (Table 1). 
 
 

A 

B 

706



y ̂(-)= 31.29 + 7.76**x - 0.93**x2
R2= 0.89

y ̂(...)=22.41 + 8.379**x - 0.96**x2
R2= 0.87

20

30

40

50

Z
n
 (

m
g
 k

g
-1

)

100% ETc 50% ETc

 

y ̂(-)=13.22 + 16.68nsx - 2.14**x2
R2= 0.81

y ̂(...)=2.79 + 19.91**x - 2.679**x2
R2= 0.96

20

30

40

50

1.8 2.8 3.8 4.8 5.8

Z
n

 (
m

g
 k

g
-1

)

Level of soil organic matter  (%)  

Figure 3: Zinc content in okra leaves depending on the levels of organic matter, irrigation with 100% (___) and 
50% ETc (---), in a soil with (A) and without mulch (B) 

 

ŷ(-)= - 63.70 + 645.15**x -75.84**x2  
R2= 0.90 

ŷ(- -)= - 30.18 + 393.47**x- 43.98**x2  
R2= 0.76 

0

400

800

1200

1600

To
ta

l w
e

ig
h

t 
o

f 
fr

u
it 

(g
/p

la
n

t)
 

 

ŷ(-)= 70.40+ 418.69**x -37.907**x2    
R2= 0,85 

ŷ(- -)=437.88 + 47.70**x - 2.267**x2   
R2= 0.77 

0

400

800

1200

1600

1,8 2,8 3,8 4,8 5,8

T
o

ta
l w

e
ig

h
t 
o

f 
fr

u
it 

(g
/p

la
n

t)
 

Level of soil organic matter (%)

100% ETc 50% ETc

 

Figure 4:  Total weight of fruit per plant  depending on the levels of organic matter, irrigation with 100% (___) 
and 50% ETc (---), in a soil with (A) and without mulch (B) 

A 

B 

A 

B 

707



The values of total green fruit weight per plant were adjusted to the quadratic regression model with maximum 
values of 1308.31 and 861.89 g/ plant (Figure 4A) and 1226.52 and 638.28 g/ plant (Figure 4B) for the plants 
that were cultivated with (4.27 and 4.52% MOS) and (5.54 and 5.8% MOS), irrigated with 100% and 50% ETc 
with and without mulch in the surface area, respectively. Comparatively, 100% ETc irrigated treatments were 
superior to those cultivated with 50% ETc with a superiority of 51.79 and 92.16% with and without mulching, 
respectively. The results are related to the effect of water stress that directly affected the variables: plant 
height, stem diameter and number of leaves and consequently fruit mass, a fact confirmed by Ferreira (2014) 
with the okra culture under the same conditions in semiarid regions. The values were also higher than the 
648.9 g/plant obtained Costa (2014), irrigating the plants with 100% ETc. 
Regarding mulching, treatments with and without mulching presented similar results. Possibly, the canopy of 
the plants cultivated in the areas without mulching, from the 40th days after sowing (DAS), in the same way as 
mulching, intercepted the sun rays not reaching the soil causing a decrease of the evaporation of water in the 
soil as well as temperature reduction. 

4. Conclusions 

The experimental result shows that the management used in this study improved the nutritional status of the 
okra plant and increased of fruit production per plant. In this way, from 1.8 to 5.8% of organic matter increased 
the boron level in the plant; to the other parameters (zinc and copper level in the plant and fruit production) 
were enough from 4 to 4.5% of organic matter in soil. The better results were obtained with the application of 
water depth of 100% ETc and with adoption of mulch.    

Acknowledgments  

The authors, acknowledge the Paraíba State University-UEPB, Campus IV, Catolé do Rocha-PB, and the 
National Council for Scientific and Technological Development-CNPq. 

Reference  

Barbosa M.A., Dantas G.F., Mesquita E.F., Nascimento F.R., Silva A.F., Sá F.V.S., Ferraz R.L.S., 2015, 
Sunflower behavior of on soils with water availability and addition of cattle biofertilizer, Afr. J. Agric. Res. 
10(41), 3913-3920.  

Costa R.A., 2014, Cultura do quiabo submetida a lâminas de irrigação por gotejamento em função da 
evaporação em tanque classe A. 54 f. Tese - Universidade Estadual Paulista “Júlio de Mesquita Filho, 
Botucatu, Brasil. 

Danso E.O., Abenney-Mickson S., Sabi E.B., Plauborg F., Abekoe M., Kugblenu Y.O., Jensen C.R., Anderson 
M.N. , 2015, Effect of different fertilization and irrigation methods on nitrogen uptake, intercepted radiation 
and yield of okra (Abelmoschus esculentum L.) grown in the Keta Sand Spit of Southeast Ghana, Agri. 
Wat. Manag. 147, 34-42. 

EMBRAPA. Centro Nacional de Pesquisa de Solos. Sistema Brasileiro de Classificação de Solos, 2013, 
Embrapa Solos, Brasília, DF. 

Ferreira D.F., 2011, Sisvar: a computer statistical analysis system, Ci. Agrot., 35(6), 1039-1042. 
Ferreira L.E., 2014, Crescimento e produção do quiabeiro irrigado com lâminas e níveis salinos da água de 

irrigação. 9 f. Tese – Universidade Federal Rural do Semiárido, Mossoró. Brasil. 
Filgueira F. A. R., 2013, Novo manual de olericultura- agrotecnologia moderna na produção e comercialização 

de hortaliças, Editora UFV, Viçosa. 
Malavolta E., Vitti G.C., Oliveira A.S., 1997, Avaliação do estado nutricional das plantas: princípios e 

aplicações. POTAFOS, Piracicaba. 
Nana R., Sawadogo M., Tamini  Z., 2014, Response of okra (Abelmoschus esculentus (L.) Moench) to water 

stress in the soil, African J Biotech., 13,  3591-3596. 
Teófilo T.M.S., Freitas F.C.L., Medeiros J.F., Fernandes D., Grangeiro L.C., Tomaz H.V.Q., Rodrigues 

A.P.M.S., 2012, Eficiência no uso da água e interferência de plantas daninhas no meloeiro cultivado nos 
sistemas de plantio direto e convencional, Plant. Dani. 30, 547-556. 

Wang Y., Wang P., 2016, Effect of organic compost mulching on orchard soil property, Chemical Engineering 
Transactions, 55, 379-384. 

708